/*
 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */

/* ======   Compiler specifics   ====== */
#if defined(_MSC_VER)
#pragma warning(disable : 4204) /* disable: C4204: non-constant aggregate initializer */
#endif

/* ======   Constants   ====== */
#define ZSTDMT_OVERLAPLOG_DEFAULT 0

/* ======   Dependencies   ====== */
#include <string.h>                 /* memcpy, memset */
#include <limits.h>                 /* INT_MAX, UINT_MAX */
#include "pool.h"                   /* threadpool */
#include "threading.h"              /* mutex */
#include "zstd_compress_internal.h" /* MIN, ERROR, ZSTD_*, ZSTD_highbit32 */
#include "zstd_ldm.h"
#include "zstdmt_compress.h"

/* Guards code to support resizing the SeqPool.
 * We will want to resize the SeqPool to save memory in the future.
 * Until then, comment the code out since it is unused.
 */
#define ZSTD_RESIZE_SEQPOOL 0

/* ======   Debug   ====== */
#if defined(DEBUGLEVEL) && (DEBUGLEVEL >= 2) && !defined(_MSC_VER) && !defined(__MINGW32__)

#include <stdio.h>
#include <unistd.h>
#include <sys/times.h>

#define DEBUG_PRINTHEX(l, p, n)                                 \
  {                                                             \
    unsigned debug_u;                                           \
    for (debug_u = 0; debug_u < (n); debug_u++)                 \
      RAWLOG(l, "%02X ", ((const unsigned char*)(p))[debug_u]); \
    RAWLOG(l, " \n");                                           \
  }

static unsigned long long GetCurrentClockTimeMicroseconds(void)
{
  static clock_t _ticksPerSecond = 0;
  if (_ticksPerSecond <= 0)
    _ticksPerSecond = sysconf(_SC_CLK_TCK);

  {
    struct tms junk;
    clock_t newTicks = (clock_t)times(&junk);
    return ((((unsigned long long)newTicks) * (1000000)) / _ticksPerSecond);
  }
}

#define MUTEX_WAIT_TIME_DLEVEL 6
#define ZSTD_PTHREAD_MUTEX_LOCK(mutex)                                                                              \
  {                                                                                                                 \
    if (DEBUGLEVEL >= MUTEX_WAIT_TIME_DLEVEL) {                                                                     \
      unsigned long long const beforeTime = GetCurrentClockTimeMicroseconds();                                      \
      ZSTD_pthread_mutex_lock(mutex);                                                                               \
      {                                                                                                             \
        unsigned long long const afterTime = GetCurrentClockTimeMicroseconds();                                     \
        unsigned long long const elapsedTime = (afterTime - beforeTime);                                            \
        if (elapsedTime > 1000) { /* or whatever threshold you like; I'm using 1 millisecond here */                \
          DEBUGLOG(                                                                                                 \
              MUTEX_WAIT_TIME_DLEVEL, "Thread took %llu microseconds to acquire mutex %s \n", elapsedTime, #mutex); \
        }                                                                                                           \
      }                                                                                                             \
    } else {                                                                                                        \
      ZSTD_pthread_mutex_lock(mutex);                                                                               \
    }                                                                                                               \
  }

#else

#define ZSTD_PTHREAD_MUTEX_LOCK(m) ZSTD_pthread_mutex_lock(m)
#define DEBUG_PRINTHEX(l, p, n) \
  {}

#endif

/* =====   Buffer Pool   ===== */
/* a single Buffer Pool can be invoked from multiple threads in parallel */

typedef struct buffer_s {
  void* start;
  size_t capacity;
} buffer_t;

static const buffer_t g_nullBuffer = {NULL, 0};

typedef struct ZSTDMT_bufferPool_s {
  ZSTD_pthread_mutex_t poolMutex;
  size_t bufferSize;
  unsigned totalBuffers;
  unsigned nbBuffers;
  ZSTD_customMem cMem;
  buffer_t bTable[1]; /* variable size */
} ZSTDMT_bufferPool;

static ZSTDMT_bufferPool* ZSTDMT_createBufferPool(unsigned nbWorkers, ZSTD_customMem cMem)
{
  unsigned const maxNbBuffers = 2 * nbWorkers + 3;
  ZSTDMT_bufferPool* const bufPool =
      (ZSTDMT_bufferPool*)ZSTD_calloc(sizeof(ZSTDMT_bufferPool) + (maxNbBuffers - 1) * sizeof(buffer_t), cMem);
  if (bufPool == NULL)
    return NULL;
  if (ZSTD_pthread_mutex_init(&bufPool->poolMutex, NULL)) {
    ZSTD_free(bufPool, cMem);
    return NULL;
  }
  bufPool->bufferSize = 64 KB;
  bufPool->totalBuffers = maxNbBuffers;
  bufPool->nbBuffers = 0;
  bufPool->cMem = cMem;
  return bufPool;
}

static void ZSTDMT_freeBufferPool(ZSTDMT_bufferPool* bufPool)
{
  unsigned u;
  DEBUGLOG(3, "ZSTDMT_freeBufferPool (address:%08X)", (U32)(size_t)bufPool);
  if (!bufPool)
    return; /* compatibility with free on NULL */
  for (u = 0; u < bufPool->totalBuffers; u++) {
    DEBUGLOG(4, "free buffer %2u (address:%08X)", u, (U32)(size_t)bufPool->bTable[u].start);
    ZSTD_free(bufPool->bTable[u].start, bufPool->cMem);
  }
  ZSTD_pthread_mutex_destroy(&bufPool->poolMutex);
  ZSTD_free(bufPool, bufPool->cMem);
}

/* only works at initialization, not during compression */
static size_t ZSTDMT_sizeof_bufferPool(ZSTDMT_bufferPool* bufPool)
{
  size_t const poolSize = sizeof(*bufPool) + (bufPool->totalBuffers - 1) * sizeof(buffer_t);
  unsigned u;
  size_t totalBufferSize = 0;
  ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
  for (u = 0; u < bufPool->totalBuffers; u++)
    totalBufferSize += bufPool->bTable[u].capacity;
  ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);

  return poolSize + totalBufferSize;
}

/* ZSTDMT_setBufferSize() :
 * all future buffers provided by this buffer pool will have _at least_ this size
 * note : it's better for all buffers to have same size,
 * as they become freely interchangeable, reducing malloc/free usages and memory fragmentation */
static void ZSTDMT_setBufferSize(ZSTDMT_bufferPool* const bufPool, size_t const bSize)
{
  ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
  DEBUGLOG(4, "ZSTDMT_setBufferSize: bSize = %u", (U32)bSize);
  bufPool->bufferSize = bSize;
  ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
}

static ZSTDMT_bufferPool* ZSTDMT_expandBufferPool(ZSTDMT_bufferPool* srcBufPool, U32 nbWorkers)
{
  unsigned const maxNbBuffers = 2 * nbWorkers + 3;
  if (srcBufPool == NULL)
    return NULL;
  if (srcBufPool->totalBuffers >= maxNbBuffers) /* good enough */
    return srcBufPool;
  /* need a larger buffer pool */
  {
    ZSTD_customMem const cMem = srcBufPool->cMem;
    size_t const bSize = srcBufPool->bufferSize; /* forward parameters */
    ZSTDMT_bufferPool* newBufPool;
    ZSTDMT_freeBufferPool(srcBufPool);
    newBufPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
    if (newBufPool == NULL)
      return newBufPool;
    ZSTDMT_setBufferSize(newBufPool, bSize);
    return newBufPool;
  }
}

/** ZSTDMT_getBuffer() :
 *  assumption : bufPool must be valid
 * @return : a buffer, with start pointer and size
 *  note: allocation may fail, in this case, start==NULL and size==0 */
static buffer_t ZSTDMT_getBuffer(ZSTDMT_bufferPool* bufPool)
{
  size_t const bSize = bufPool->bufferSize;
  DEBUGLOG(5, "ZSTDMT_getBuffer: bSize = %u", (U32)bufPool->bufferSize);
  ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
  if (bufPool->nbBuffers) { /* try to use an existing buffer */
    buffer_t const buf = bufPool->bTable[--(bufPool->nbBuffers)];
    size_t const availBufferSize = buf.capacity;
    bufPool->bTable[bufPool->nbBuffers] = g_nullBuffer;
    if ((availBufferSize >= bSize) & ((availBufferSize >> 3) <= bSize)) {
      /* large enough, but not too much */
      DEBUGLOG(5, "ZSTDMT_getBuffer: provide buffer %u of size %u", bufPool->nbBuffers, (U32)buf.capacity);
      ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
      return buf;
    }
    /* size conditions not respected : scratch this buffer, create new one */
    DEBUGLOG(5, "ZSTDMT_getBuffer: existing buffer does not meet size conditions => freeing");
    ZSTD_free(buf.start, bufPool->cMem);
  }
  ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
  /* create new buffer */
  DEBUGLOG(5, "ZSTDMT_getBuffer: create a new buffer");
  {
    buffer_t buffer;
    void* const start = ZSTD_malloc(bSize, bufPool->cMem);
    buffer.start = start; /* note : start can be NULL if malloc fails ! */
    buffer.capacity = (start == NULL) ? 0 : bSize;
    if (start == NULL) {
      DEBUGLOG(5, "ZSTDMT_getBuffer: buffer allocation failure !!");
    } else {
      DEBUGLOG(5, "ZSTDMT_getBuffer: created buffer of size %u", (U32)bSize);
    }
    return buffer;
  }
}

#if ZSTD_RESIZE_SEQPOOL
/** ZSTDMT_resizeBuffer() :
 * assumption : bufPool must be valid
 * @return : a buffer that is at least the buffer pool buffer size.
 *           If a reallocation happens, the data in the input buffer is copied.
 */
static buffer_t ZSTDMT_resizeBuffer(ZSTDMT_bufferPool* bufPool, buffer_t buffer)
{
  size_t const bSize = bufPool->bufferSize;
  if (buffer.capacity < bSize) {
    void* const start = ZSTD_malloc(bSize, bufPool->cMem);
    buffer_t newBuffer;
    newBuffer.start = start;
    newBuffer.capacity = start == NULL ? 0 : bSize;
    if (start != NULL) {
      assert(newBuffer.capacity >= buffer.capacity);
      memcpy(newBuffer.start, buffer.start, buffer.capacity);
      DEBUGLOG(5, "ZSTDMT_resizeBuffer: created buffer of size %u", (U32)bSize);
      return newBuffer;
    }
    DEBUGLOG(5, "ZSTDMT_resizeBuffer: buffer allocation failure !!");
  }
  return buffer;
}
#endif

/* store buffer for later re-use, up to pool capacity */
static void ZSTDMT_releaseBuffer(ZSTDMT_bufferPool* bufPool, buffer_t buf)
{
  DEBUGLOG(5, "ZSTDMT_releaseBuffer");
  if (buf.start == NULL)
    return; /* compatible with release on NULL */
  ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
  if (bufPool->nbBuffers < bufPool->totalBuffers) {
    bufPool->bTable[bufPool->nbBuffers++] = buf; /* stored for later use */
    DEBUGLOG(5,
        "ZSTDMT_releaseBuffer: stored buffer of size %u in slot %u",
        (U32)buf.capacity,
        (U32)(bufPool->nbBuffers - 1));
    ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
    return;
  }
  ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
  /* Reached bufferPool capacity (should not happen) */
  DEBUGLOG(5, "ZSTDMT_releaseBuffer: pool capacity reached => freeing ");
  ZSTD_free(buf.start, bufPool->cMem);
}

/* =====   Seq Pool Wrapper   ====== */

static rawSeqStore_t kNullRawSeqStore = {NULL, 0, 0, 0};

typedef ZSTDMT_bufferPool ZSTDMT_seqPool;

static size_t ZSTDMT_sizeof_seqPool(ZSTDMT_seqPool* seqPool)
{
  return ZSTDMT_sizeof_bufferPool(seqPool);
}

static rawSeqStore_t bufferToSeq(buffer_t buffer)
{
  rawSeqStore_t seq = {NULL, 0, 0, 0};
  seq.seq = (rawSeq*)buffer.start;
  seq.capacity = buffer.capacity / sizeof(rawSeq);
  return seq;
}

static buffer_t seqToBuffer(rawSeqStore_t seq)
{
  buffer_t buffer;
  buffer.start = seq.seq;
  buffer.capacity = seq.capacity * sizeof(rawSeq);
  return buffer;
}

static rawSeqStore_t ZSTDMT_getSeq(ZSTDMT_seqPool* seqPool)
{
  if (seqPool->bufferSize == 0) {
    return kNullRawSeqStore;
  }
  return bufferToSeq(ZSTDMT_getBuffer(seqPool));
}

#if ZSTD_RESIZE_SEQPOOL
static rawSeqStore_t ZSTDMT_resizeSeq(ZSTDMT_seqPool* seqPool, rawSeqStore_t seq)
{
  return bufferToSeq(ZSTDMT_resizeBuffer(seqPool, seqToBuffer(seq)));
}
#endif

static void ZSTDMT_releaseSeq(ZSTDMT_seqPool* seqPool, rawSeqStore_t seq)
{
  ZSTDMT_releaseBuffer(seqPool, seqToBuffer(seq));
}

static void ZSTDMT_setNbSeq(ZSTDMT_seqPool* const seqPool, size_t const nbSeq)
{
  ZSTDMT_setBufferSize(seqPool, nbSeq * sizeof(rawSeq));
}

static ZSTDMT_seqPool* ZSTDMT_createSeqPool(unsigned nbWorkers, ZSTD_customMem cMem)
{
  ZSTDMT_seqPool* const seqPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
  if (seqPool == NULL)
    return NULL;
  ZSTDMT_setNbSeq(seqPool, 0);
  return seqPool;
}

static void ZSTDMT_freeSeqPool(ZSTDMT_seqPool* seqPool)
{
  ZSTDMT_freeBufferPool(seqPool);
}

static ZSTDMT_seqPool* ZSTDMT_expandSeqPool(ZSTDMT_seqPool* pool, U32 nbWorkers)
{
  return ZSTDMT_expandBufferPool(pool, nbWorkers);
}

/* =====   CCtx Pool   ===== */
/* a single CCtx Pool can be invoked from multiple threads in parallel */

typedef struct {
  ZSTD_pthread_mutex_t poolMutex;
  int totalCCtx;
  int availCCtx;
  ZSTD_customMem cMem;
  ZSTD_CCtx* cctx[1]; /* variable size */
} ZSTDMT_CCtxPool;

/* note : all CCtx borrowed from the pool should be released back to the pool _before_ freeing the pool */
static void ZSTDMT_freeCCtxPool(ZSTDMT_CCtxPool* pool)
{
  int cid;
  for (cid = 0; cid < pool->totalCCtx; cid++)
    ZSTD_freeCCtx(pool->cctx[cid]); /* note : compatible with free on NULL */
  ZSTD_pthread_mutex_destroy(&pool->poolMutex);
  ZSTD_free(pool, pool->cMem);
}

/* ZSTDMT_createCCtxPool() :
 * implies nbWorkers >= 1 , checked by caller ZSTDMT_createCCtx() */
static ZSTDMT_CCtxPool* ZSTDMT_createCCtxPool(int nbWorkers, ZSTD_customMem cMem)
{
  ZSTDMT_CCtxPool* const cctxPool =
      (ZSTDMT_CCtxPool*)ZSTD_calloc(sizeof(ZSTDMT_CCtxPool) + (nbWorkers - 1) * sizeof(ZSTD_CCtx*), cMem);
  assert(nbWorkers > 0);
  if (!cctxPool)
    return NULL;
  if (ZSTD_pthread_mutex_init(&cctxPool->poolMutex, NULL)) {
    ZSTD_free(cctxPool, cMem);
    return NULL;
  }
  cctxPool->cMem = cMem;
  cctxPool->totalCCtx = nbWorkers;
  cctxPool->availCCtx = 1; /* at least one cctx for single-thread mode */
  cctxPool->cctx[0] = ZSTD_createCCtx_advanced(cMem);
  if (!cctxPool->cctx[0]) {
    ZSTDMT_freeCCtxPool(cctxPool);
    return NULL;
  }
  DEBUGLOG(3, "cctxPool created, with %u workers", nbWorkers);
  return cctxPool;
}

static ZSTDMT_CCtxPool* ZSTDMT_expandCCtxPool(ZSTDMT_CCtxPool* srcPool, int nbWorkers)
{
  if (srcPool == NULL)
    return NULL;
  if (nbWorkers <= srcPool->totalCCtx)
    return srcPool; /* good enough */
  /* need a larger cctx pool */
  {
    ZSTD_customMem const cMem = srcPool->cMem;
    ZSTDMT_freeCCtxPool(srcPool);
    return ZSTDMT_createCCtxPool(nbWorkers, cMem);
  }
}

/* only works during initialization phase, not during compression */
static size_t ZSTDMT_sizeof_CCtxPool(ZSTDMT_CCtxPool* cctxPool)
{
  ZSTD_pthread_mutex_lock(&cctxPool->poolMutex);
  {
    unsigned const nbWorkers = cctxPool->totalCCtx;
    size_t const poolSize = sizeof(*cctxPool) + (nbWorkers - 1) * sizeof(ZSTD_CCtx*);
    unsigned u;
    size_t totalCCtxSize = 0;
    for (u = 0; u < nbWorkers; u++) {
      totalCCtxSize += ZSTD_sizeof_CCtx(cctxPool->cctx[u]);
    }
    ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
    assert(nbWorkers > 0);
    return poolSize + totalCCtxSize;
  }
}

static ZSTD_CCtx* ZSTDMT_getCCtx(ZSTDMT_CCtxPool* cctxPool)
{
  DEBUGLOG(5, "ZSTDMT_getCCtx");
  ZSTD_pthread_mutex_lock(&cctxPool->poolMutex);
  if (cctxPool->availCCtx) {
    cctxPool->availCCtx--;
    {
      ZSTD_CCtx* const cctx = cctxPool->cctx[cctxPool->availCCtx];
      ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
      return cctx;
    }
  }
  ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
  DEBUGLOG(5, "create one more CCtx");
  return ZSTD_createCCtx_advanced(cctxPool->cMem); /* note : can be NULL, when creation fails ! */
}

static void ZSTDMT_releaseCCtx(ZSTDMT_CCtxPool* pool, ZSTD_CCtx* cctx)
{
  if (cctx == NULL)
    return; /* compatibility with release on NULL */
  ZSTD_pthread_mutex_lock(&pool->poolMutex);
  if (pool->availCCtx < pool->totalCCtx)
    pool->cctx[pool->availCCtx++] = cctx;
  else {
    /* pool overflow : should not happen, since totalCCtx==nbWorkers */
    DEBUGLOG(4, "CCtx pool overflow : free cctx");
    ZSTD_freeCCtx(cctx);
  }
  ZSTD_pthread_mutex_unlock(&pool->poolMutex);
}

/* ====   Serial State   ==== */

typedef struct {
  void const* start;
  size_t size;
} range_t;

typedef struct {
  /* All variables in the struct are protected by mutex. */
  ZSTD_pthread_mutex_t mutex;
  ZSTD_pthread_cond_t cond;
  ZSTD_CCtx_params params;
  ldmState_t ldmState;
  XXH64_state_t xxhState;
  unsigned nextJobID;
  /* Protects ldmWindow.
   * Must be acquired after the main mutex when acquiring both.
   */
  ZSTD_pthread_mutex_t ldmWindowMutex;
  ZSTD_pthread_cond_t ldmWindowCond; /* Signaled when ldmWindow is udpated */
  ZSTD_window_t ldmWindow;           /* A thread-safe copy of ldmState.window */
} serialState_t;

static int ZSTDMT_serialState_reset(
    serialState_t* serialState, ZSTDMT_seqPool* seqPool, ZSTD_CCtx_params params, size_t jobSize)
{
  /* Adjust parameters */
  if (params.ldmParams.enableLdm) {
    DEBUGLOG(4, "LDM window size = %u KB", (1U << params.cParams.windowLog) >> 10);
    ZSTD_ldm_adjustParameters(&params.ldmParams, &params.cParams);
    assert(params.ldmParams.hashLog >= params.ldmParams.bucketSizeLog);
    assert(params.ldmParams.hashRateLog < 32);
    serialState->ldmState.hashPower = ZSTD_rollingHash_primePower(params.ldmParams.minMatchLength);
  } else {
    memset(&params.ldmParams, 0, sizeof(params.ldmParams));
  }
  serialState->nextJobID = 0;
  if (params.fParams.checksumFlag)
    XXH64_reset(&serialState->xxhState, 0);
  if (params.ldmParams.enableLdm) {
    ZSTD_customMem cMem = params.customMem;
    unsigned const hashLog = params.ldmParams.hashLog;
    size_t const hashSize = ((size_t)1 << hashLog) * sizeof(ldmEntry_t);
    unsigned const bucketLog = params.ldmParams.hashLog - params.ldmParams.bucketSizeLog;
    size_t const bucketSize = (size_t)1 << bucketLog;
    unsigned const prevBucketLog = serialState->params.ldmParams.hashLog - serialState->params.ldmParams.bucketSizeLog;
    /* Size the seq pool tables */
    ZSTDMT_setNbSeq(seqPool, ZSTD_ldm_getMaxNbSeq(params.ldmParams, jobSize));
    /* Reset the window */
    ZSTD_window_clear(&serialState->ldmState.window);
    serialState->ldmWindow = serialState->ldmState.window;
    /* Resize tables and output space if necessary. */
    if (serialState->ldmState.hashTable == NULL || serialState->params.ldmParams.hashLog < hashLog) {
      ZSTD_free(serialState->ldmState.hashTable, cMem);
      serialState->ldmState.hashTable = (ldmEntry_t*)ZSTD_malloc(hashSize, cMem);
    }
    if (serialState->ldmState.bucketOffsets == NULL || prevBucketLog < bucketLog) {
      ZSTD_free(serialState->ldmState.bucketOffsets, cMem);
      serialState->ldmState.bucketOffsets = (BYTE*)ZSTD_malloc(bucketSize, cMem);
    }
    if (!serialState->ldmState.hashTable || !serialState->ldmState.bucketOffsets)
      return 1;
    /* Zero the tables */
    memset(serialState->ldmState.hashTable, 0, hashSize);
    memset(serialState->ldmState.bucketOffsets, 0, bucketSize);
  }
  serialState->params = params;
  serialState->params.jobSize = (U32)jobSize;
  return 0;
}

static int ZSTDMT_serialState_init(serialState_t* serialState)
{
  int initError = 0;
  memset(serialState, 0, sizeof(*serialState));
  initError |= ZSTD_pthread_mutex_init(&serialState->mutex, NULL);
  initError |= ZSTD_pthread_cond_init(&serialState->cond, NULL);
  initError |= ZSTD_pthread_mutex_init(&serialState->ldmWindowMutex, NULL);
  initError |= ZSTD_pthread_cond_init(&serialState->ldmWindowCond, NULL);
  return initError;
}

static void ZSTDMT_serialState_free(serialState_t* serialState)
{
  ZSTD_customMem cMem = serialState->params.customMem;
  ZSTD_pthread_mutex_destroy(&serialState->mutex);
  ZSTD_pthread_cond_destroy(&serialState->cond);
  ZSTD_pthread_mutex_destroy(&serialState->ldmWindowMutex);
  ZSTD_pthread_cond_destroy(&serialState->ldmWindowCond);
  ZSTD_free(serialState->ldmState.hashTable, cMem);
  ZSTD_free(serialState->ldmState.bucketOffsets, cMem);
}

static void ZSTDMT_serialState_update(
    serialState_t* serialState, ZSTD_CCtx* jobCCtx, rawSeqStore_t seqStore, range_t src, unsigned jobID)
{
  /* Wait for our turn */
  ZSTD_PTHREAD_MUTEX_LOCK(&serialState->mutex);
  while (serialState->nextJobID < jobID) {
    DEBUGLOG(5, "wait for serialState->cond");
    ZSTD_pthread_cond_wait(&serialState->cond, &serialState->mutex);
  }
  /* A future job may error and skip our job */
  if (serialState->nextJobID == jobID) {
    /* It is now our turn, do any processing necessary */
    if (serialState->params.ldmParams.enableLdm) {
      size_t error;
      assert(seqStore.seq != NULL && seqStore.pos == 0 && seqStore.size == 0 && seqStore.capacity > 0);
      assert(src.size <= serialState->params.jobSize);
      ZSTD_window_update(&serialState->ldmState.window, src.start, src.size);
      error = ZSTD_ldm_generateSequences(
          &serialState->ldmState, &seqStore, &serialState->params.ldmParams, src.start, src.size);
      /* We provide a large enough buffer to never fail. */
      assert(!ZSTD_isError(error));
      (void)error;
      /* Update ldmWindow to match the ldmState.window and signal the main
       * thread if it is waiting for a buffer.
       */
      ZSTD_PTHREAD_MUTEX_LOCK(&serialState->ldmWindowMutex);
      serialState->ldmWindow = serialState->ldmState.window;
      ZSTD_pthread_cond_signal(&serialState->ldmWindowCond);
      ZSTD_pthread_mutex_unlock(&serialState->ldmWindowMutex);
    }
    if (serialState->params.fParams.checksumFlag && src.size > 0)
      XXH64_update(&serialState->xxhState, src.start, src.size);
  }
  /* Now it is the next jobs turn */
  serialState->nextJobID++;
  ZSTD_pthread_cond_broadcast(&serialState->cond);
  ZSTD_pthread_mutex_unlock(&serialState->mutex);

  if (seqStore.size > 0) {
    size_t const err = ZSTD_referenceExternalSequences(jobCCtx, seqStore.seq, seqStore.size);
    assert(serialState->params.ldmParams.enableLdm);
    assert(!ZSTD_isError(err));
    (void)err;
  }
}

static void ZSTDMT_serialState_ensureFinished(serialState_t* serialState, unsigned jobID, size_t cSize)
{
  ZSTD_PTHREAD_MUTEX_LOCK(&serialState->mutex);
  if (serialState->nextJobID <= jobID) {
    assert(ZSTD_isError(cSize));
    (void)cSize;
    DEBUGLOG(5, "Skipping past job %u because of error", jobID);
    serialState->nextJobID = jobID + 1;
    ZSTD_pthread_cond_broadcast(&serialState->cond);

    ZSTD_PTHREAD_MUTEX_LOCK(&serialState->ldmWindowMutex);
    ZSTD_window_clear(&serialState->ldmWindow);
    ZSTD_pthread_cond_signal(&serialState->ldmWindowCond);
    ZSTD_pthread_mutex_unlock(&serialState->ldmWindowMutex);
  }
  ZSTD_pthread_mutex_unlock(&serialState->mutex);
}

/* ------------------------------------------ */
/* =====          Worker thread         ===== */
/* ------------------------------------------ */

static const range_t kNullRange = {NULL, 0};

typedef struct {
  size_t consumed; /* SHARED - set0 by mtctx, then modified by worker AND read by mtctx */
  size_t cSize;    /* SHARED - set0 by mtctx, then modified by worker AND read by mtctx, then set0 by mtctx */
  ZSTD_pthread_mutex_t job_mutex; /* Thread-safe - used by mtctx and worker */
  ZSTD_pthread_cond_t job_cond;   /* Thread-safe - used by mtctx and worker */
  ZSTDMT_CCtxPool* cctxPool;      /* Thread-safe - used by mtctx and (all) workers */
  ZSTDMT_bufferPool* bufPool;     /* Thread-safe - used by mtctx and (all) workers */
  ZSTDMT_seqPool* seqPool;        /* Thread-safe - used by mtctx and (all) workers */
  serialState_t* serial;          /* Thread-safe - used by mtctx and (all) workers */
  buffer_t dstBuff;  /* set by worker (or mtctx), then read by worker & mtctx, then modified by mtctx => no barrier */
  range_t prefix;    /* set by mtctx, then read by worker & mtctx => no barrier */
  range_t src;       /* set by mtctx, then read by worker & mtctx => no barrier */
  unsigned jobID;    /* set by mtctx, then read by worker => no barrier */
  unsigned firstJob; /* set by mtctx, then read by worker => no barrier */
  unsigned lastJob;  /* set by mtctx, then read by worker => no barrier */
  ZSTD_CCtx_params params;          /* set by mtctx, then read by worker => no barrier */
  const ZSTD_CDict* cdict;          /* set by mtctx, then read by worker => no barrier */
  unsigned long long fullFrameSize; /* set by mtctx, then read by worker => no barrier */
  size_t dstFlushed;                /* used only by mtctx */
  unsigned frameChecksumNeeded;     /* used only by mtctx */
} ZSTDMT_jobDescription;

#define JOB_ERROR(e)                            \
  {                                             \
    ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);   \
    job->cSize = e;                             \
    ZSTD_pthread_mutex_unlock(&job->job_mutex); \
    goto _endJob;                               \
  }

/* ZSTDMT_compressionJob() is a POOL_function type */
static void ZSTDMT_compressionJob(void* jobDescription)
{
  ZSTDMT_jobDescription* const job = (ZSTDMT_jobDescription*)jobDescription;
  ZSTD_CCtx_params jobParams = job->params; /* do not modify job->params ! copy it, modify the copy */
  ZSTD_CCtx* const cctx = ZSTDMT_getCCtx(job->cctxPool);
  rawSeqStore_t rawSeqStore = ZSTDMT_getSeq(job->seqPool);
  buffer_t dstBuff = job->dstBuff;
  size_t lastCBlockSize = 0;

  /* ressources */
  if (cctx == NULL)
    JOB_ERROR(ERROR(memory_allocation));
  if (dstBuff.start == NULL) { /* streaming job : doesn't provide a dstBuffer */
    dstBuff = ZSTDMT_getBuffer(job->bufPool);
    if (dstBuff.start == NULL)
      JOB_ERROR(ERROR(memory_allocation));
    job->dstBuff = dstBuff; /* this value can be read in ZSTDMT_flush, when it copies the whole job */
  }
  if (jobParams.ldmParams.enableLdm && rawSeqStore.seq == NULL)
    JOB_ERROR(ERROR(memory_allocation));

  /* Don't compute the checksum for chunks, since we compute it externally,
   * but write it in the header.
   */
  if (job->jobID != 0)
    jobParams.fParams.checksumFlag = 0;
  /* Don't run LDM for the chunks, since we handle it externally */
  jobParams.ldmParams.enableLdm = 0;

  /* init */
  if (job->cdict) {
    size_t const initError = ZSTD_compressBegin_advanced_internal(
        cctx, NULL, 0, ZSTD_dct_auto, ZSTD_dtlm_fast, job->cdict, jobParams, job->fullFrameSize);
    assert(job->firstJob); /* only allowed for first job */
    if (ZSTD_isError(initError))
      JOB_ERROR(initError);
  } else { /* srcStart points at reloaded section */
    U64 const pledgedSrcSize = job->firstJob ? job->fullFrameSize : job->src.size;
    {
      size_t const forceWindowError = ZSTD_CCtxParam_setParameter(&jobParams, ZSTD_c_forceMaxWindow, !job->firstJob);
      if (ZSTD_isError(forceWindowError))
        JOB_ERROR(forceWindowError);
    }
    {
      size_t const initError = ZSTD_compressBegin_advanced_internal(cctx,
          job->prefix.start,
          job->prefix.size,
          ZSTD_dct_rawContent, /* load dictionary in "content-only" mode (no header analysis) */
          ZSTD_dtlm_fast,
          NULL, /*cdict*/
          jobParams,
          pledgedSrcSize);
      if (ZSTD_isError(initError))
        JOB_ERROR(initError);
    }
  }

  /* Perform serial step as early as possible, but after CCtx initialization */
  ZSTDMT_serialState_update(job->serial, cctx, rawSeqStore, job->src, job->jobID);

  if (!job->firstJob) { /* flush and overwrite frame header when it's not first job */
    size_t const hSize = ZSTD_compressContinue(cctx, dstBuff.start, dstBuff.capacity, job->src.start, 0);
    if (ZSTD_isError(hSize))
      JOB_ERROR(hSize);
    DEBUGLOG(5, "ZSTDMT_compressionJob: flush and overwrite %u bytes of frame header (not first job)", (U32)hSize);
    ZSTD_invalidateRepCodes(cctx);
  }

  /* compress */
  {
    size_t const chunkSize = 4 * ZSTD_BLOCKSIZE_MAX;
    int const nbChunks = (int)((job->src.size + (chunkSize - 1)) / chunkSize);
    const BYTE* ip = (const BYTE*)job->src.start;
    BYTE* const ostart = (BYTE*)dstBuff.start;
    BYTE* op = ostart;
    BYTE* oend = op + dstBuff.capacity;
    int chunkNb;
    if (sizeof(size_t) > sizeof(int))
      assert(job->src.size < ((size_t)INT_MAX) * chunkSize); /* check overflow */
    DEBUGLOG(5, "ZSTDMT_compressionJob: compress %u bytes in %i blocks", (U32)job->src.size, nbChunks);
    assert(job->cSize == 0);
    for (chunkNb = 1; chunkNb < nbChunks; chunkNb++) {
      size_t const cSize = ZSTD_compressContinue(cctx, op, oend - op, ip, chunkSize);
      if (ZSTD_isError(cSize))
        JOB_ERROR(cSize);
      ip += chunkSize;
      op += cSize;
      assert(op < oend);
      /* stats */
      ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);
      job->cSize += cSize;
      job->consumed = chunkSize * chunkNb;
      DEBUGLOG(
          5, "ZSTDMT_compressionJob: compress new block : cSize==%u bytes (total: %u)", (U32)cSize, (U32)job->cSize);
      ZSTD_pthread_cond_signal(&job->job_cond); /* warns some more data is ready to be flushed */
      ZSTD_pthread_mutex_unlock(&job->job_mutex);
    }
    /* last block */
    assert(chunkSize > 0);
    assert((chunkSize & (chunkSize - 1)) == 0); /* chunkSize must be power of 2 for mask==(chunkSize-1) to work */
    if ((nbChunks > 0) | job->lastJob /*must output a "last block" flag*/) {
      size_t const lastBlockSize1 = job->src.size & (chunkSize - 1);
      size_t const lastBlockSize = ((lastBlockSize1 == 0) & (job->src.size >= chunkSize)) ? chunkSize : lastBlockSize1;
      size_t const cSize = (job->lastJob) ? ZSTD_compressEnd(cctx, op, oend - op, ip, lastBlockSize)
                                          : ZSTD_compressContinue(cctx, op, oend - op, ip, lastBlockSize);
      if (ZSTD_isError(cSize))
        JOB_ERROR(cSize);
      lastCBlockSize = cSize;
    }
  }

_endJob:
  ZSTDMT_serialState_ensureFinished(job->serial, job->jobID, job->cSize);
  if (job->prefix.size > 0)
    DEBUGLOG(5, "Finished with prefix: %zx", (size_t)job->prefix.start);
  DEBUGLOG(5, "Finished with source: %zx", (size_t)job->src.start);
  /* release resources */
  ZSTDMT_releaseSeq(job->seqPool, rawSeqStore);
  ZSTDMT_releaseCCtx(job->cctxPool, cctx);
  /* report */
  ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);
  if (ZSTD_isError(job->cSize))
    assert(lastCBlockSize == 0);
  job->cSize += lastCBlockSize;
  job->consumed = job->src.size; /* when job->consumed == job->src.size , compression job is presumed completed */
  ZSTD_pthread_cond_signal(&job->job_cond);
  ZSTD_pthread_mutex_unlock(&job->job_mutex);
}

/* ------------------------------------------ */
/* =====   Multi-threaded compression   ===== */
/* ------------------------------------------ */

typedef struct {
  range_t prefix; /* read-only non-owned prefix buffer */
  buffer_t buffer;
  size_t filled;
} inBuff_t;

typedef struct {
  BYTE* buffer;    /* The round input buffer. All jobs get references
                    * to pieces of the buffer. ZSTDMT_tryGetInputRange()
                    * handles handing out job input buffers, and makes
                    * sure it doesn't overlap with any pieces still in use.
                    */
  size_t capacity; /* The capacity of buffer. */
  size_t pos;      /* The position of the current inBuff in the round
                    * buffer. Updated past the end if the inBuff once
                    * the inBuff is sent to the worker thread.
                    * pos <= capacity.
                    */
} roundBuff_t;

static const roundBuff_t kNullRoundBuff = {NULL, 0, 0};

#define RSYNC_LENGTH 32

typedef struct {
  U64 hash;
  U64 hitMask;
  U64 primePower;
} rsyncState_t;

struct ZSTDMT_CCtx_s {
  POOL_ctx* factory;
  ZSTDMT_jobDescription* jobs;
  ZSTDMT_bufferPool* bufPool;
  ZSTDMT_CCtxPool* cctxPool;
  ZSTDMT_seqPool* seqPool;
  ZSTD_CCtx_params params;
  size_t targetSectionSize;
  size_t targetPrefixSize;
  int jobReady; /* 1 => one job is already prepared, but pool has shortage of workers. Don't create a new job. */
  inBuff_t inBuff;
  roundBuff_t roundBuff;
  serialState_t serial;
  rsyncState_t rsync;
  unsigned singleBlockingThread;
  unsigned jobIDMask;
  unsigned doneJobID;
  unsigned nextJobID;
  unsigned frameEnded;
  unsigned allJobsCompleted;
  unsigned long long frameContentSize;
  unsigned long long consumed;
  unsigned long long produced;
  ZSTD_customMem cMem;
  ZSTD_CDict* cdictLocal;
  const ZSTD_CDict* cdict;
};

static void ZSTDMT_freeJobsTable(ZSTDMT_jobDescription* jobTable, U32 nbJobs, ZSTD_customMem cMem)
{
  U32 jobNb;
  if (jobTable == NULL)
    return;
  for (jobNb = 0; jobNb < nbJobs; jobNb++) {
    ZSTD_pthread_mutex_destroy(&jobTable[jobNb].job_mutex);
    ZSTD_pthread_cond_destroy(&jobTable[jobNb].job_cond);
  }
  ZSTD_free(jobTable, cMem);
}

/* ZSTDMT_allocJobsTable()
 * allocate and init a job table.
 * update *nbJobsPtr to next power of 2 value, as size of table */
static ZSTDMT_jobDescription* ZSTDMT_createJobsTable(U32* nbJobsPtr, ZSTD_customMem cMem)
{
  U32 const nbJobsLog2 = ZSTD_highbit32(*nbJobsPtr) + 1;
  U32 const nbJobs = 1 << nbJobsLog2;
  U32 jobNb;
  ZSTDMT_jobDescription* const jobTable =
      (ZSTDMT_jobDescription*)ZSTD_calloc(nbJobs * sizeof(ZSTDMT_jobDescription), cMem);
  int initError = 0;
  if (jobTable == NULL)
    return NULL;
  *nbJobsPtr = nbJobs;
  for (jobNb = 0; jobNb < nbJobs; jobNb++) {
    initError |= ZSTD_pthread_mutex_init(&jobTable[jobNb].job_mutex, NULL);
    initError |= ZSTD_pthread_cond_init(&jobTable[jobNb].job_cond, NULL);
  }
  if (initError != 0) {
    ZSTDMT_freeJobsTable(jobTable, nbJobs, cMem);
    return NULL;
  }
  return jobTable;
}

static size_t ZSTDMT_expandJobsTable(ZSTDMT_CCtx* mtctx, U32 nbWorkers)
{
  U32 nbJobs = nbWorkers + 2;
  if (nbJobs > mtctx->jobIDMask + 1) { /* need more job capacity */
    ZSTDMT_freeJobsTable(mtctx->jobs, mtctx->jobIDMask + 1, mtctx->cMem);
    mtctx->jobIDMask = 0;
    mtctx->jobs = ZSTDMT_createJobsTable(&nbJobs, mtctx->cMem);
    if (mtctx->jobs == NULL)
      return ERROR(memory_allocation);
    assert((nbJobs != 0) && ((nbJobs & (nbJobs - 1)) == 0)); /* ensure nbJobs is a power of 2 */
    mtctx->jobIDMask = nbJobs - 1;
  }
  return 0;
}

/* ZSTDMT_CCtxParam_setNbWorkers():
 * Internal use only */
size_t ZSTDMT_CCtxParam_setNbWorkers(ZSTD_CCtx_params* params, unsigned nbWorkers)
{
  if (nbWorkers > ZSTDMT_NBWORKERS_MAX)
    nbWorkers = ZSTDMT_NBWORKERS_MAX;
  params->nbWorkers = nbWorkers;
  params->overlapLog = ZSTDMT_OVERLAPLOG_DEFAULT;
  params->jobSize = 0;
  return nbWorkers;
}

ZSTDMT_CCtx* ZSTDMT_createCCtx_advanced(unsigned nbWorkers, ZSTD_customMem cMem)
{
  ZSTDMT_CCtx* mtctx;
  U32 nbJobs = nbWorkers + 2;
  int initError;
  DEBUGLOG(3, "ZSTDMT_createCCtx_advanced (nbWorkers = %u)", nbWorkers);

  if (nbWorkers < 1)
    return NULL;
  nbWorkers = MIN(nbWorkers, ZSTDMT_NBWORKERS_MAX);
  if ((cMem.customAlloc != NULL) ^ (cMem.customFree != NULL))
    /* invalid custom allocator */
    return NULL;

  mtctx = (ZSTDMT_CCtx*)ZSTD_calloc(sizeof(ZSTDMT_CCtx), cMem);
  if (!mtctx)
    return NULL;
  ZSTDMT_CCtxParam_setNbWorkers(&mtctx->params, nbWorkers);
  mtctx->cMem = cMem;
  mtctx->allJobsCompleted = 1;
  mtctx->factory = POOL_create_advanced(nbWorkers, 0, cMem);
  mtctx->jobs = ZSTDMT_createJobsTable(&nbJobs, cMem);
  assert(nbJobs > 0);
  assert((nbJobs & (nbJobs - 1)) == 0); /* ensure nbJobs is a power of 2 */
  mtctx->jobIDMask = nbJobs - 1;
  mtctx->bufPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
  mtctx->cctxPool = ZSTDMT_createCCtxPool(nbWorkers, cMem);
  mtctx->seqPool = ZSTDMT_createSeqPool(nbWorkers, cMem);
  initError = ZSTDMT_serialState_init(&mtctx->serial);
  mtctx->roundBuff = kNullRoundBuff;
  if (!mtctx->factory | !mtctx->jobs | !mtctx->bufPool | !mtctx->cctxPool | !mtctx->seqPool | initError) {
    ZSTDMT_freeCCtx(mtctx);
    return NULL;
  }
  DEBUGLOG(3, "mt_cctx created, for %u threads", nbWorkers);
  return mtctx;
}

ZSTDMT_CCtx* ZSTDMT_createCCtx(unsigned nbWorkers)
{
  return ZSTDMT_createCCtx_advanced(nbWorkers, ZSTD_defaultCMem);
}

/* ZSTDMT_releaseAllJobResources() :
 * note : ensure all workers are killed first ! */
static void ZSTDMT_releaseAllJobResources(ZSTDMT_CCtx* mtctx)
{
  unsigned jobID;
  DEBUGLOG(3, "ZSTDMT_releaseAllJobResources");
  for (jobID = 0; jobID <= mtctx->jobIDMask; jobID++) {
    DEBUGLOG(4, "job%02u: release dst address %08X", jobID, (U32)(size_t)mtctx->jobs[jobID].dstBuff.start);
    ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[jobID].dstBuff);
    mtctx->jobs[jobID].dstBuff = g_nullBuffer;
    mtctx->jobs[jobID].cSize = 0;
  }
  memset(mtctx->jobs, 0, (mtctx->jobIDMask + 1) * sizeof(ZSTDMT_jobDescription));
  mtctx->inBuff.buffer = g_nullBuffer;
  mtctx->inBuff.filled = 0;
  mtctx->allJobsCompleted = 1;
}

static void ZSTDMT_waitForAllJobsCompleted(ZSTDMT_CCtx* mtctx)
{
  DEBUGLOG(4, "ZSTDMT_waitForAllJobsCompleted");
  while (mtctx->doneJobID < mtctx->nextJobID) {
    unsigned const jobID = mtctx->doneJobID & mtctx->jobIDMask;
    ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[jobID].job_mutex);
    while (mtctx->jobs[jobID].consumed < mtctx->jobs[jobID].src.size) {
      DEBUGLOG(4,
          "waiting for jobCompleted signal from job %u",
          mtctx->doneJobID); /* we want to block when waiting for data to flush */
      ZSTD_pthread_cond_wait(&mtctx->jobs[jobID].job_cond, &mtctx->jobs[jobID].job_mutex);
    }
    ZSTD_pthread_mutex_unlock(&mtctx->jobs[jobID].job_mutex);
    mtctx->doneJobID++;
  }
}

size_t ZSTDMT_freeCCtx(ZSTDMT_CCtx* mtctx)
{
  if (mtctx == NULL)
    return 0;                           /* compatible with free on NULL */
  POOL_free(mtctx->factory);            /* stop and free worker threads */
  ZSTDMT_releaseAllJobResources(mtctx); /* release job resources into pools first */
  ZSTDMT_freeJobsTable(mtctx->jobs, mtctx->jobIDMask + 1, mtctx->cMem);
  ZSTDMT_freeBufferPool(mtctx->bufPool);
  ZSTDMT_freeCCtxPool(mtctx->cctxPool);
  ZSTDMT_freeSeqPool(mtctx->seqPool);
  ZSTDMT_serialState_free(&mtctx->serial);
  ZSTD_freeCDict(mtctx->cdictLocal);
  if (mtctx->roundBuff.buffer)
    ZSTD_free(mtctx->roundBuff.buffer, mtctx->cMem);
  ZSTD_free(mtctx, mtctx->cMem);
  return 0;
}

size_t ZSTDMT_sizeof_CCtx(ZSTDMT_CCtx* mtctx)
{
  if (mtctx == NULL)
    return 0; /* supports sizeof NULL */
  return sizeof(*mtctx) + POOL_sizeof(mtctx->factory) + ZSTDMT_sizeof_bufferPool(mtctx->bufPool) +
         (mtctx->jobIDMask + 1) * sizeof(ZSTDMT_jobDescription) + ZSTDMT_sizeof_CCtxPool(mtctx->cctxPool) +
         ZSTDMT_sizeof_seqPool(mtctx->seqPool) + ZSTD_sizeof_CDict(mtctx->cdictLocal) + mtctx->roundBuff.capacity;
}

/* Internal only */
size_t ZSTDMT_CCtxParam_setMTCtxParameter(ZSTD_CCtx_params* params, ZSTDMT_parameter parameter, int value)
{
  DEBUGLOG(4, "ZSTDMT_CCtxParam_setMTCtxParameter");
  switch (parameter) {
    case ZSTDMT_p_jobSize:
      DEBUGLOG(4, "ZSTDMT_CCtxParam_setMTCtxParameter : set jobSize to %i", value);
      if (value != 0 /* default */
          && value < ZSTDMT_JOBSIZE_MIN)
        value = ZSTDMT_JOBSIZE_MIN;
      assert(value >= 0);
      if (value > ZSTDMT_JOBSIZE_MAX)
        value = ZSTDMT_JOBSIZE_MAX;
      params->jobSize = value;
      return value;

    case ZSTDMT_p_overlapLog:
      DEBUGLOG(4, "ZSTDMT_p_overlapLog : %i", value);
      if (value < ZSTD_OVERLAPLOG_MIN)
        value = ZSTD_OVERLAPLOG_MIN;
      if (value > ZSTD_OVERLAPLOG_MAX)
        value = ZSTD_OVERLAPLOG_MAX;
      params->overlapLog = value;
      return value;

    case ZSTDMT_p_rsyncable:
      value = (value != 0);
      params->rsyncable = value;
      return value;

    default:
      return ERROR(parameter_unsupported);
  }
}

size_t ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, int value)
{
  DEBUGLOG(4, "ZSTDMT_setMTCtxParameter");
  return ZSTDMT_CCtxParam_setMTCtxParameter(&mtctx->params, parameter, value);
}

size_t ZSTDMT_getMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, int* value)
{
  switch (parameter) {
    case ZSTDMT_p_jobSize:
      assert(mtctx->params.jobSize <= INT_MAX);
      *value = (int)(mtctx->params.jobSize);
      break;
    case ZSTDMT_p_overlapLog:
      *value = mtctx->params.overlapLog;
      break;
    case ZSTDMT_p_rsyncable:
      *value = mtctx->params.rsyncable;
      break;
    default:
      return ERROR(parameter_unsupported);
  }
  return 0;
}

/* Sets parameters relevant to the compression job,
 * initializing others to default values. */
static ZSTD_CCtx_params ZSTDMT_initJobCCtxParams(ZSTD_CCtx_params const params)
{
  ZSTD_CCtx_params jobParams;
  memset(&jobParams, 0, sizeof(jobParams));

  jobParams.cParams = params.cParams;
  jobParams.fParams = params.fParams;
  jobParams.compressionLevel = params.compressionLevel;

  return jobParams;
}

/* ZSTDMT_resize() :
 * @return : error code if fails, 0 on success */
static size_t ZSTDMT_resize(ZSTDMT_CCtx* mtctx, unsigned nbWorkers)
{
  if (POOL_resize(mtctx->factory, nbWorkers))
    return ERROR(memory_allocation);
  CHECK_F(ZSTDMT_expandJobsTable(mtctx, nbWorkers));
  mtctx->bufPool = ZSTDMT_expandBufferPool(mtctx->bufPool, nbWorkers);
  if (mtctx->bufPool == NULL)
    return ERROR(memory_allocation);
  mtctx->cctxPool = ZSTDMT_expandCCtxPool(mtctx->cctxPool, nbWorkers);
  if (mtctx->cctxPool == NULL)
    return ERROR(memory_allocation);
  mtctx->seqPool = ZSTDMT_expandSeqPool(mtctx->seqPool, nbWorkers);
  if (mtctx->seqPool == NULL)
    return ERROR(memory_allocation);
  ZSTDMT_CCtxParam_setNbWorkers(&mtctx->params, nbWorkers);
  return 0;
}

/*! ZSTDMT_updateCParams_whileCompressing() :
 *  Updates a selected set of compression parameters, remaining compatible with currently active frame.
 *  New parameters will be applied to next compression job. */
void ZSTDMT_updateCParams_whileCompressing(ZSTDMT_CCtx* mtctx, const ZSTD_CCtx_params* cctxParams)
{
  U32 const saved_wlog = mtctx->params.cParams.windowLog; /* Do not modify windowLog while compressing */
  int const compressionLevel = cctxParams->compressionLevel;
  DEBUGLOG(5, "ZSTDMT_updateCParams_whileCompressing (level:%i)", compressionLevel);
  mtctx->params.compressionLevel = compressionLevel;
  {
    ZSTD_compressionParameters cParams = ZSTD_getCParamsFromCCtxParams(cctxParams, 0, 0);
    cParams.windowLog = saved_wlog;
    mtctx->params.cParams = cParams;
  }
}

/* ZSTDMT_getFrameProgression():
 * tells how much data has been consumed (input) and produced (output) for current frame.
 * able to count progression inside worker threads.
 * Note : mutex will be acquired during statistics collection inside workers. */
ZSTD_frameProgression ZSTDMT_getFrameProgression(ZSTDMT_CCtx* mtctx)
{
  ZSTD_frameProgression fps;
  DEBUGLOG(5, "ZSTDMT_getFrameProgression");
  fps.ingested = mtctx->consumed + mtctx->inBuff.filled;
  fps.consumed = mtctx->consumed;
  fps.produced = fps.flushed = mtctx->produced;
  fps.currentJobID = mtctx->nextJobID;
  fps.nbActiveWorkers = 0;
  {
    unsigned jobNb;
    unsigned lastJobNb = mtctx->nextJobID + mtctx->jobReady;
    assert(mtctx->jobReady <= 1);
    DEBUGLOG(6,
        "ZSTDMT_getFrameProgression: jobs: from %u to <%u (jobReady:%u)",
        mtctx->doneJobID,
        lastJobNb,
        mtctx->jobReady)
    for (jobNb = mtctx->doneJobID; jobNb < lastJobNb; jobNb++) {
      unsigned const wJobID = jobNb & mtctx->jobIDMask;
      ZSTDMT_jobDescription* jobPtr = &mtctx->jobs[wJobID];
      ZSTD_pthread_mutex_lock(&jobPtr->job_mutex);
      {
        size_t const cResult = jobPtr->cSize;
        size_t const produced = ZSTD_isError(cResult) ? 0 : cResult;
        size_t const flushed = ZSTD_isError(cResult) ? 0 : jobPtr->dstFlushed;
        assert(flushed <= produced);
        fps.ingested += jobPtr->src.size;
        fps.consumed += jobPtr->consumed;
        fps.produced += produced;
        fps.flushed += flushed;
        fps.nbActiveWorkers += (jobPtr->consumed < jobPtr->src.size);
      }
      ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
    }
  }
  return fps;
}

size_t ZSTDMT_toFlushNow(ZSTDMT_CCtx* mtctx)
{
  size_t toFlush;
  unsigned const jobID = mtctx->doneJobID;
  assert(jobID <= mtctx->nextJobID);
  if (jobID == mtctx->nextJobID)
    return 0; /* no active job => nothing to flush */

  /* look into oldest non-fully-flushed job */
  {
    unsigned const wJobID = jobID & mtctx->jobIDMask;
    ZSTDMT_jobDescription* const jobPtr = &mtctx->jobs[wJobID];
    ZSTD_pthread_mutex_lock(&jobPtr->job_mutex);
    {
      size_t const cResult = jobPtr->cSize;
      size_t const produced = ZSTD_isError(cResult) ? 0 : cResult;
      size_t const flushed = ZSTD_isError(cResult) ? 0 : jobPtr->dstFlushed;
      assert(flushed <= produced);
      toFlush = produced - flushed;
      if (toFlush == 0 && (jobPtr->consumed >= jobPtr->src.size)) {
        /* doneJobID is not-fully-flushed, but toFlush==0 : doneJobID should be compressing some more data */
        assert(jobPtr->consumed < jobPtr->src.size);
      }
    }
    ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
  }

  return toFlush;
}

/* ------------------------------------------ */
/* =====   Multi-threaded compression   ===== */
/* ------------------------------------------ */

static unsigned ZSTDMT_computeTargetJobLog(ZSTD_CCtx_params const params)
{
  if (params.ldmParams.enableLdm)
    /* In Long Range Mode, the windowLog is typically oversized.
     * In which case, it's preferable to determine the jobSize
     * based on chainLog instead. */
    return MAX(21, params.cParams.chainLog + 4);
  return MAX(20, params.cParams.windowLog + 2);
}

static int ZSTDMT_overlapLog_default(ZSTD_strategy strat)
{
  switch (strat) {
    case ZSTD_btultra2:
      return 9;
    case ZSTD_btultra:
    case ZSTD_btopt:
      return 8;
    case ZSTD_btlazy2:
    case ZSTD_lazy2:
      return 7;
    case ZSTD_lazy:
    case ZSTD_greedy:
    case ZSTD_dfast:
    case ZSTD_fast:
    default:;
  }
  return 6;
}

static int ZSTDMT_overlapLog(int ovlog, ZSTD_strategy strat)
{
  assert(0 <= ovlog && ovlog <= 9);
  if (ovlog == 0)
    return ZSTDMT_overlapLog_default(strat);
  return ovlog;
}

static size_t ZSTDMT_computeOverlapSize(ZSTD_CCtx_params const params)
{
  int const overlapRLog = 9 - ZSTDMT_overlapLog(params.overlapLog, params.cParams.strategy);
  int ovLog = (overlapRLog >= 8) ? 0 : (params.cParams.windowLog - overlapRLog);
  assert(0 <= overlapRLog && overlapRLog <= 8);
  if (params.ldmParams.enableLdm) {
    /* In Long Range Mode, the windowLog is typically oversized.
     * In which case, it's preferable to determine the jobSize
     * based on chainLog instead.
     * Then, ovLog becomes a fraction of the jobSize, rather than windowSize */
    ovLog = MIN(params.cParams.windowLog, ZSTDMT_computeTargetJobLog(params) - 2) - overlapRLog;
  }
  assert(0 <= ovLog && ovLog <= 30);
  DEBUGLOG(4, "overlapLog : %i", params.overlapLog);
  DEBUGLOG(4, "overlap size : %i", 1 << ovLog);
  return (ovLog == 0) ? 0 : (size_t)1 << ovLog;
}

static unsigned ZSTDMT_computeNbJobs(ZSTD_CCtx_params params, size_t srcSize, unsigned nbWorkers)
{
  assert(nbWorkers > 0);
  {
    size_t const jobSizeTarget = (size_t)1 << ZSTDMT_computeTargetJobLog(params);
    size_t const jobMaxSize = jobSizeTarget << 2;
    size_t const passSizeMax = jobMaxSize * nbWorkers;
    unsigned const multiplier = (unsigned)(srcSize / passSizeMax) + 1;
    unsigned const nbJobsLarge = multiplier * nbWorkers;
    unsigned const nbJobsMax = (unsigned)(srcSize / jobSizeTarget) + 1;
    unsigned const nbJobsSmall = MIN(nbJobsMax, nbWorkers);
    return (multiplier > 1) ? nbJobsLarge : nbJobsSmall;
  }
}

/* ZSTDMT_compress_advanced_internal() :
 * This is a blocking function : it will only give back control to caller after finishing its compression job.
 */
static size_t ZSTDMT_compress_advanced_internal(ZSTDMT_CCtx* mtctx, void* dst, size_t dstCapacity, const void* src,
    size_t srcSize, const ZSTD_CDict* cdict, ZSTD_CCtx_params params)
{
  ZSTD_CCtx_params const jobParams = ZSTDMT_initJobCCtxParams(params);
  size_t const overlapSize = ZSTDMT_computeOverlapSize(params);
  unsigned const nbJobs = ZSTDMT_computeNbJobs(params, srcSize, params.nbWorkers);
  size_t const proposedJobSize = (srcSize + (nbJobs - 1)) / nbJobs;
  size_t const avgJobSize = (((proposedJobSize - 1) & 0x1FFFF) < 0x7FFF)
                                ? proposedJobSize + 0xFFFF
                                : proposedJobSize; /* avoid too small last block */
  const char* const srcStart = (const char*)src;
  size_t remainingSrcSize = srcSize;
  unsigned const compressWithinDst =
      (dstCapacity >= ZSTD_compressBound(srcSize))
          ? nbJobs
          : (unsigned)(dstCapacity /
                       ZSTD_compressBound(avgJobSize)); /* presumes avgJobSize >= 256 KB, which should be the case */
  size_t frameStartPos = 0, dstBufferPos = 0;
  assert(jobParams.nbWorkers == 0);
  assert(mtctx->cctxPool->totalCCtx == params.nbWorkers);

  params.jobSize = (U32)avgJobSize;
  DEBUGLOG(4,
      "ZSTDMT_compress_advanced_internal: nbJobs=%2u (rawSize=%u bytes; fixedSize=%u) ",
      nbJobs,
      (U32)proposedJobSize,
      (U32)avgJobSize);

  if ((nbJobs == 1) |
      (params.nbWorkers <= 1)) { /* fallback to single-thread mode : this is a blocking invocation anyway */
    ZSTD_CCtx* const cctx = mtctx->cctxPool->cctx[0];
    DEBUGLOG(4, "ZSTDMT_compress_advanced_internal: fallback to single-thread mode");
    if (cdict)
      return ZSTD_compress_usingCDict_advanced(cctx, dst, dstCapacity, src, srcSize, cdict, jobParams.fParams);
    return ZSTD_compress_advanced_internal(cctx, dst, dstCapacity, src, srcSize, NULL, 0, jobParams);
  }

  assert(
      avgJobSize >= 256 KB); /* condition for ZSTD_compressBound(A) + ZSTD_compressBound(B) <= ZSTD_compressBound(A+B),
                                required to compress directly into Dst (no additional buffer) */
  ZSTDMT_setBufferSize(mtctx->bufPool, ZSTD_compressBound(avgJobSize));
  if (ZSTDMT_serialState_reset(&mtctx->serial, mtctx->seqPool, params, avgJobSize))
    return ERROR(memory_allocation);

  CHECK_F(ZSTDMT_expandJobsTable(mtctx, nbJobs)); /* only expands if necessary */

  {
    unsigned u;
    for (u = 0; u < nbJobs; u++) {
      size_t const jobSize = MIN(remainingSrcSize, avgJobSize);
      size_t const dstBufferCapacity = ZSTD_compressBound(jobSize);
      buffer_t const dstAsBuffer = {(char*)dst + dstBufferPos, dstBufferCapacity};
      buffer_t const dstBuffer = u < compressWithinDst ? dstAsBuffer : g_nullBuffer;
      size_t dictSize = u ? overlapSize : 0;

      mtctx->jobs[u].prefix.start = srcStart + frameStartPos - dictSize;
      mtctx->jobs[u].prefix.size = dictSize;
      mtctx->jobs[u].src.start = srcStart + frameStartPos;
      mtctx->jobs[u].src.size = jobSize;
      assert(jobSize > 0); /* avoid job.src.size == 0 */
      mtctx->jobs[u].consumed = 0;
      mtctx->jobs[u].cSize = 0;
      mtctx->jobs[u].cdict = (u == 0) ? cdict : NULL;
      mtctx->jobs[u].fullFrameSize = srcSize;
      mtctx->jobs[u].params = jobParams;
      /* do not calculate checksum within sections, but write it in header for first section */
      mtctx->jobs[u].dstBuff = dstBuffer;
      mtctx->jobs[u].cctxPool = mtctx->cctxPool;
      mtctx->jobs[u].bufPool = mtctx->bufPool;
      mtctx->jobs[u].seqPool = mtctx->seqPool;
      mtctx->jobs[u].serial = &mtctx->serial;
      mtctx->jobs[u].jobID = u;
      mtctx->jobs[u].firstJob = (u == 0);
      mtctx->jobs[u].lastJob = (u == nbJobs - 1);

      DEBUGLOG(5, "ZSTDMT_compress_advanced_internal: posting job %u  (%u bytes)", u, (U32)jobSize);
      DEBUG_PRINTHEX(6, mtctx->jobs[u].prefix.start, 12);
      POOL_add(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[u]);

      frameStartPos += jobSize;
      dstBufferPos += dstBufferCapacity;
      remainingSrcSize -= jobSize;
    }
  }

  /* collect result */
  {
    size_t error = 0, dstPos = 0;
    unsigned jobID;
    for (jobID = 0; jobID < nbJobs; jobID++) {
      DEBUGLOG(5, "waiting for job %u ", jobID);
      ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[jobID].job_mutex);
      while (mtctx->jobs[jobID].consumed < mtctx->jobs[jobID].src.size) {
        DEBUGLOG(5, "waiting for jobCompleted signal from job %u", jobID);
        ZSTD_pthread_cond_wait(&mtctx->jobs[jobID].job_cond, &mtctx->jobs[jobID].job_mutex);
      }
      ZSTD_pthread_mutex_unlock(&mtctx->jobs[jobID].job_mutex);
      DEBUGLOG(5, "ready to write job %u ", jobID);

      {
        size_t const cSize = mtctx->jobs[jobID].cSize;
        if (ZSTD_isError(cSize))
          error = cSize;
        if ((!error) && (dstPos + cSize > dstCapacity))
          error = ERROR(dstSize_tooSmall);
        if (jobID) { /* note : job 0 is written directly at dst, which is correct position */
          if (!error)
            memmove((char*)dst + dstPos,
                mtctx->jobs[jobID].dstBuff.start,
                cSize);                     /* may overlap when job compressed within dst */
          if (jobID >= compressWithinDst) { /* job compressed into its own buffer, which must be released */
            DEBUGLOG(5, "releasing buffer %u>=%u", jobID, compressWithinDst);
            ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[jobID].dstBuff);
          }
        }
        mtctx->jobs[jobID].dstBuff = g_nullBuffer;
        mtctx->jobs[jobID].cSize = 0;
        dstPos += cSize;
      }
    } /* for (jobID=0; jobID<nbJobs; jobID++) */

    DEBUGLOG(4, "checksumFlag : %u ", params.fParams.checksumFlag);
    if (params.fParams.checksumFlag) {
      U32 const checksum = (U32)XXH64_digest(&mtctx->serial.xxhState);
      if (dstPos + 4 > dstCapacity) {
        error = ERROR(dstSize_tooSmall);
      } else {
        DEBUGLOG(4, "writing checksum : %08X \n", checksum);
        MEM_writeLE32((char*)dst + dstPos, checksum);
        dstPos += 4;
      }
    }

    if (!error)
      DEBUGLOG(4, "compressed size : %u  ", (U32)dstPos);
    return error ? error : dstPos;
  }
}

size_t ZSTDMT_compress_advanced(ZSTDMT_CCtx* mtctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize,
    const ZSTD_CDict* cdict, ZSTD_parameters params, int overlapLog)
{
  ZSTD_CCtx_params cctxParams = mtctx->params;
  cctxParams.cParams = params.cParams;
  cctxParams.fParams = params.fParams;
  assert(ZSTD_OVERLAPLOG_MIN <= overlapLog && overlapLog <= ZSTD_OVERLAPLOG_MAX);
  cctxParams.overlapLog = overlapLog;
  return ZSTDMT_compress_advanced_internal(mtctx, dst, dstCapacity, src, srcSize, cdict, cctxParams);
}

size_t ZSTDMT_compressCCtx(
    ZSTDMT_CCtx* mtctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel)
{
  ZSTD_parameters params = ZSTD_getParams(compressionLevel, srcSize, 0);
  int const overlapLog = ZSTDMT_overlapLog_default(params.cParams.strategy);
  params.fParams.contentSizeFlag = 1;
  return ZSTDMT_compress_advanced(mtctx, dst, dstCapacity, src, srcSize, NULL, params, overlapLog);
}

/* ====================================== */
/* =======      Streaming API     ======= */
/* ====================================== */

size_t ZSTDMT_initCStream_internal(ZSTDMT_CCtx* mtctx, const void* dict, size_t dictSize,
    ZSTD_dictContentType_e dictContentType, const ZSTD_CDict* cdict, ZSTD_CCtx_params params,
    unsigned long long pledgedSrcSize)
{
  DEBUGLOG(4,
      "ZSTDMT_initCStream_internal (pledgedSrcSize=%u, nbWorkers=%u, cctxPool=%u)",
      (U32)pledgedSrcSize,
      params.nbWorkers,
      mtctx->cctxPool->totalCCtx);

  /* params supposed partially fully validated at this point */
  assert(!ZSTD_isError(ZSTD_checkCParams(params.cParams)));
  assert(!((dict) && (cdict))); /* either dict or cdict, not both */

  /* init */
  if (params.nbWorkers != mtctx->params.nbWorkers)
    CHECK_F(ZSTDMT_resize(mtctx, params.nbWorkers));

  if (params.jobSize != 0 && params.jobSize < ZSTDMT_JOBSIZE_MIN)
    params.jobSize = ZSTDMT_JOBSIZE_MIN;
  if (params.jobSize > (size_t)ZSTDMT_JOBSIZE_MAX)
    params.jobSize = ZSTDMT_JOBSIZE_MAX;

  mtctx->singleBlockingThread =
      (pledgedSrcSize <= ZSTDMT_JOBSIZE_MIN); /* do not trigger multi-threading when srcSize is too small */
  if (mtctx->singleBlockingThread) {
    ZSTD_CCtx_params const singleThreadParams = ZSTDMT_initJobCCtxParams(params);
    DEBUGLOG(5, "ZSTDMT_initCStream_internal: switch to single blocking thread mode");
    assert(singleThreadParams.nbWorkers == 0);
    return ZSTD_initCStream_internal(
        mtctx->cctxPool->cctx[0], dict, dictSize, cdict, singleThreadParams, pledgedSrcSize);
  }

  DEBUGLOG(4, "ZSTDMT_initCStream_internal: %u workers", params.nbWorkers);

  if (mtctx->allJobsCompleted == 0) { /* previous compression not correctly finished */
    ZSTDMT_waitForAllJobsCompleted(mtctx);
    ZSTDMT_releaseAllJobResources(mtctx);
    mtctx->allJobsCompleted = 1;
  }

  mtctx->params = params;
  mtctx->frameContentSize = pledgedSrcSize;
  if (dict) {
    ZSTD_freeCDict(mtctx->cdictLocal);
    mtctx->cdictLocal = ZSTD_createCDict_advanced(dict,
        dictSize,
        ZSTD_dlm_byCopy,
        dictContentType, /* note : a loadPrefix becomes an internal CDict */
        params.cParams,
        mtctx->cMem);
    mtctx->cdict = mtctx->cdictLocal;
    if (mtctx->cdictLocal == NULL)
      return ERROR(memory_allocation);
  } else {
    ZSTD_freeCDict(mtctx->cdictLocal);
    mtctx->cdictLocal = NULL;
    mtctx->cdict = cdict;
  }

  mtctx->targetPrefixSize = ZSTDMT_computeOverlapSize(params);
  DEBUGLOG(4, "overlapLog=%i => %u KB", params.overlapLog, (U32)(mtctx->targetPrefixSize >> 10));
  mtctx->targetSectionSize = params.jobSize;
  if (mtctx->targetSectionSize == 0) {
    mtctx->targetSectionSize = 1ULL << ZSTDMT_computeTargetJobLog(params);
  }
  if (params.rsyncable) {
    /* Aim for the targetsectionSize as the average job size. */
    U32 const jobSizeMB = (U32)(mtctx->targetSectionSize >> 20);
    U32 const rsyncBits = ZSTD_highbit32(jobSizeMB) + 20;
    assert(jobSizeMB >= 1);
    DEBUGLOG(4, "rsyncLog = %u", rsyncBits);
    mtctx->rsync.hash = 0;
    mtctx->rsync.hitMask = (1ULL << rsyncBits) - 1;
    mtctx->rsync.primePower = ZSTD_rollingHash_primePower(RSYNC_LENGTH);
  }
  if (mtctx->targetSectionSize < mtctx->targetPrefixSize)
    mtctx->targetSectionSize = mtctx->targetPrefixSize; /* job size must be >= overlap size */
  DEBUGLOG(4, "Job Size : %u KB (note : set to %u)", (U32)(mtctx->targetSectionSize >> 10), (U32)params.jobSize);
  DEBUGLOG(4, "inBuff Size : %u KB", (U32)(mtctx->targetSectionSize >> 10));
  ZSTDMT_setBufferSize(mtctx->bufPool, ZSTD_compressBound(mtctx->targetSectionSize));
  {
    /* If ldm is enabled we need windowSize space. */
    size_t const windowSize = mtctx->params.ldmParams.enableLdm ? (1U << mtctx->params.cParams.windowLog) : 0;
    /* Two buffers of slack, plus extra space for the overlap
     * This is the minimum slack that LDM works with. One extra because
     * flush might waste up to targetSectionSize-1 bytes. Another extra
     * for the overlap (if > 0), then one to fill which doesn't overlap
     * with the LDM window.
     */
    size_t const nbSlackBuffers = 2 + (mtctx->targetPrefixSize > 0);
    size_t const slackSize = mtctx->targetSectionSize * nbSlackBuffers;
    /* Compute the total size, and always have enough slack */
    size_t const nbWorkers = MAX(mtctx->params.nbWorkers, 1);
    size_t const sectionsSize = mtctx->targetSectionSize * nbWorkers;
    size_t const capacity = MAX(windowSize, sectionsSize) + slackSize;
    if (mtctx->roundBuff.capacity < capacity) {
      if (mtctx->roundBuff.buffer)
        ZSTD_free(mtctx->roundBuff.buffer, mtctx->cMem);
      mtctx->roundBuff.buffer = (BYTE*)ZSTD_malloc(capacity, mtctx->cMem);
      if (mtctx->roundBuff.buffer == NULL) {
        mtctx->roundBuff.capacity = 0;
        return ERROR(memory_allocation);
      }
      mtctx->roundBuff.capacity = capacity;
    }
  }
  DEBUGLOG(4, "roundBuff capacity : %u KB", (U32)(mtctx->roundBuff.capacity >> 10));
  mtctx->roundBuff.pos = 0;
  mtctx->inBuff.buffer = g_nullBuffer;
  mtctx->inBuff.filled = 0;
  mtctx->inBuff.prefix = kNullRange;
  mtctx->doneJobID = 0;
  mtctx->nextJobID = 0;
  mtctx->frameEnded = 0;
  mtctx->allJobsCompleted = 0;
  mtctx->consumed = 0;
  mtctx->produced = 0;
  if (ZSTDMT_serialState_reset(&mtctx->serial, mtctx->seqPool, params, mtctx->targetSectionSize))
    return ERROR(memory_allocation);
  return 0;
}

size_t ZSTDMT_initCStream_advanced(
    ZSTDMT_CCtx* mtctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize)
{
  ZSTD_CCtx_params cctxParams = mtctx->params; /* retrieve sticky params */
  DEBUGLOG(4, "ZSTDMT_initCStream_advanced (pledgedSrcSize=%u)", (U32)pledgedSrcSize);
  cctxParams.cParams = params.cParams;
  cctxParams.fParams = params.fParams;
  return ZSTDMT_initCStream_internal(mtctx, dict, dictSize, ZSTD_dct_auto, NULL, cctxParams, pledgedSrcSize);
}

size_t ZSTDMT_initCStream_usingCDict(
    ZSTDMT_CCtx* mtctx, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize)
{
  ZSTD_CCtx_params cctxParams = mtctx->params;
  if (cdict == NULL)
    return ERROR(dictionary_wrong); /* method incompatible with NULL cdict */
  cctxParams.cParams = ZSTD_getCParamsFromCDict(cdict);
  cctxParams.fParams = fParams;
  return ZSTDMT_initCStream_internal(mtctx, NULL, 0 /*dictSize*/, ZSTD_dct_auto, cdict, cctxParams, pledgedSrcSize);
}

/* ZSTDMT_resetCStream() :
 * pledgedSrcSize can be zero == unknown (for the time being)
 * prefer using ZSTD_CONTENTSIZE_UNKNOWN,
 * as `0` might mean "empty" in the future */
size_t ZSTDMT_resetCStream(ZSTDMT_CCtx* mtctx, unsigned long long pledgedSrcSize)
{
  if (!pledgedSrcSize)
    pledgedSrcSize = ZSTD_CONTENTSIZE_UNKNOWN;
  return ZSTDMT_initCStream_internal(mtctx, NULL, 0, ZSTD_dct_auto, 0, mtctx->params, pledgedSrcSize);
}

size_t ZSTDMT_initCStream(ZSTDMT_CCtx* mtctx, int compressionLevel)
{
  ZSTD_parameters const params = ZSTD_getParams(compressionLevel, ZSTD_CONTENTSIZE_UNKNOWN, 0);
  ZSTD_CCtx_params cctxParams = mtctx->params; /* retrieve sticky params */
  DEBUGLOG(4, "ZSTDMT_initCStream (cLevel=%i)", compressionLevel);
  cctxParams.cParams = params.cParams;
  cctxParams.fParams = params.fParams;
  return ZSTDMT_initCStream_internal(mtctx, NULL, 0, ZSTD_dct_auto, NULL, cctxParams, ZSTD_CONTENTSIZE_UNKNOWN);
}

/* ZSTDMT_writeLastEmptyBlock()
 * Write a single empty block with an end-of-frame to finish a frame.
 * Job must be created from streaming variant.
 * This function is always successfull if expected conditions are fulfilled.
 */
static void ZSTDMT_writeLastEmptyBlock(ZSTDMT_jobDescription* job)
{
  assert(job->lastJob == 1);
  assert(job->src.size == 0); /* last job is empty -> will be simplified into a last empty block */
  assert(job->firstJob == 0); /* cannot be first job, as it also needs to create frame header */
  assert(
      job->dstBuff.start == NULL); /* invoked from streaming variant only (otherwise, dstBuff might be user's output) */
  job->dstBuff = ZSTDMT_getBuffer(job->bufPool);
  if (job->dstBuff.start == NULL) {
    job->cSize = ERROR(memory_allocation);
    return;
  }
  assert(job->dstBuff.capacity >= ZSTD_blockHeaderSize); /* no buffer should ever be that small */
  job->src = kNullRange;
  job->cSize = ZSTD_writeLastEmptyBlock(job->dstBuff.start, job->dstBuff.capacity);
  assert(!ZSTD_isError(job->cSize));
  assert(job->consumed == 0);
}

static size_t ZSTDMT_createCompressionJob(ZSTDMT_CCtx* mtctx, size_t srcSize, ZSTD_EndDirective endOp)
{
  unsigned const jobID = mtctx->nextJobID & mtctx->jobIDMask;
  int const endFrame = (endOp == ZSTD_e_end);

  if (mtctx->nextJobID > mtctx->doneJobID + mtctx->jobIDMask) {
    DEBUGLOG(5, "ZSTDMT_createCompressionJob: will not create new job : table is full");
    assert((mtctx->nextJobID & mtctx->jobIDMask) == (mtctx->doneJobID & mtctx->jobIDMask));
    return 0;
  }

  if (!mtctx->jobReady) {
    BYTE const* src = (BYTE const*)mtctx->inBuff.buffer.start;
    DEBUGLOG(5,
        "ZSTDMT_createCompressionJob: preparing job %u to compress %u bytes with %u preload ",
        mtctx->nextJobID,
        (U32)srcSize,
        (U32)mtctx->inBuff.prefix.size);
    mtctx->jobs[jobID].src.start = src;
    mtctx->jobs[jobID].src.size = srcSize;
    assert(mtctx->inBuff.filled >= srcSize);
    mtctx->jobs[jobID].prefix = mtctx->inBuff.prefix;
    mtctx->jobs[jobID].consumed = 0;
    mtctx->jobs[jobID].cSize = 0;
    mtctx->jobs[jobID].params = mtctx->params;
    mtctx->jobs[jobID].cdict = mtctx->nextJobID == 0 ? mtctx->cdict : NULL;
    mtctx->jobs[jobID].fullFrameSize = mtctx->frameContentSize;
    mtctx->jobs[jobID].dstBuff = g_nullBuffer;
    mtctx->jobs[jobID].cctxPool = mtctx->cctxPool;
    mtctx->jobs[jobID].bufPool = mtctx->bufPool;
    mtctx->jobs[jobID].seqPool = mtctx->seqPool;
    mtctx->jobs[jobID].serial = &mtctx->serial;
    mtctx->jobs[jobID].jobID = mtctx->nextJobID;
    mtctx->jobs[jobID].firstJob = (mtctx->nextJobID == 0);
    mtctx->jobs[jobID].lastJob = endFrame;
    mtctx->jobs[jobID].frameChecksumNeeded = mtctx->params.fParams.checksumFlag && endFrame && (mtctx->nextJobID > 0);
    mtctx->jobs[jobID].dstFlushed = 0;

    /* Update the round buffer pos and clear the input buffer to be reset */
    mtctx->roundBuff.pos += srcSize;
    mtctx->inBuff.buffer = g_nullBuffer;
    mtctx->inBuff.filled = 0;
    /* Set the prefix */
    if (!endFrame) {
      size_t const newPrefixSize = MIN(srcSize, mtctx->targetPrefixSize);
      mtctx->inBuff.prefix.start = src + srcSize - newPrefixSize;
      mtctx->inBuff.prefix.size = newPrefixSize;
    } else { /* endFrame==1 => no need for another input buffer */
      mtctx->inBuff.prefix = kNullRange;
      mtctx->frameEnded = endFrame;
      if (mtctx->nextJobID == 0) {
        /* single job exception : checksum is already calculated directly within worker thread */
        mtctx->params.fParams.checksumFlag = 0;
      }
    }

    if ((srcSize == 0) && (mtctx->nextJobID > 0) /*single job must also write frame header*/) {
      DEBUGLOG(5, "ZSTDMT_createCompressionJob: creating a last empty block to end frame");
      assert(endOp == ZSTD_e_end); /* only possible case : need to end the frame with an empty last block */
      ZSTDMT_writeLastEmptyBlock(mtctx->jobs + jobID);
      mtctx->nextJobID++;
      return 0;
    }
  }

  DEBUGLOG(5,
      "ZSTDMT_createCompressionJob: posting job %u : %u bytes  (end:%u, jobNb == %u (mod:%u))",
      mtctx->nextJobID,
      (U32)mtctx->jobs[jobID].src.size,
      mtctx->jobs[jobID].lastJob,
      mtctx->nextJobID,
      jobID);
  if (POOL_tryAdd(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[jobID])) {
    mtctx->nextJobID++;
    mtctx->jobReady = 0;
  } else {
    DEBUGLOG(5, "ZSTDMT_createCompressionJob: no worker available for job %u", mtctx->nextJobID);
    mtctx->jobReady = 1;
  }
  return 0;
}

/*! ZSTDMT_flushProduced() :
 *  flush whatever data has been produced but not yet flushed in current job.
 *  move to next job if current one is fully flushed.
 * `output` : `pos` will be updated with amount of data flushed .
 * `blockToFlush` : if >0, the function will block and wait if there is no data available to flush .
 * @return : amount of data remaining within internal buffer, 0 if no more, 1 if unknown but > 0, or an error code */
static size_t ZSTDMT_flushProduced(
    ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, unsigned blockToFlush, ZSTD_EndDirective end)
{
  unsigned const wJobID = mtctx->doneJobID & mtctx->jobIDMask;
  DEBUGLOG(5, "ZSTDMT_flushProduced (blocking:%u , job %u <= %u)", blockToFlush, mtctx->doneJobID, mtctx->nextJobID);
  assert(output->size >= output->pos);

  ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[wJobID].job_mutex);
  if (blockToFlush && (mtctx->doneJobID < mtctx->nextJobID)) {
    assert(mtctx->jobs[wJobID].dstFlushed <= mtctx->jobs[wJobID].cSize);
    while (mtctx->jobs[wJobID].dstFlushed == mtctx->jobs[wJobID].cSize) { /* nothing to flush */
      if (mtctx->jobs[wJobID].consumed == mtctx->jobs[wJobID].src.size) {
        DEBUGLOG(5,
            "job %u is completely consumed (%u == %u) => don't wait for cond, there will be none",
            mtctx->doneJobID,
            (U32)mtctx->jobs[wJobID].consumed,
            (U32)mtctx->jobs[wJobID].src.size);
        break;
      }
      DEBUGLOG(5,
          "waiting for something to flush from job %u (currently flushed: %u bytes)",
          mtctx->doneJobID,
          (U32)mtctx->jobs[wJobID].dstFlushed);
      ZSTD_pthread_cond_wait(&mtctx->jobs[wJobID].job_cond,
          &mtctx->jobs[wJobID].job_mutex); /* block when nothing to flush but some to come */
    }
  }

  /* try to flush something */
  {
    size_t cSize = mtctx->jobs[wJobID].cSize;                /* shared */
    size_t const srcConsumed = mtctx->jobs[wJobID].consumed; /* shared */
    size_t const srcSize = mtctx->jobs[wJobID].src.size;     /* read-only, could be done after mutex lock, but
                                                                no-declaration-after-statement */
    ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
    if (ZSTD_isError(cSize)) {
      DEBUGLOG(5,
          "ZSTDMT_flushProduced: job %u : compression error detected : %s",
          mtctx->doneJobID,
          ZSTD_getErrorName(cSize));
      ZSTDMT_waitForAllJobsCompleted(mtctx);
      ZSTDMT_releaseAllJobResources(mtctx);
      return cSize;
    }
    /* add frame checksum if necessary (can only happen once) */
    assert(srcConsumed <= srcSize);
    if ((srcConsumed == srcSize) /* job completed -> worker no longer active */
        && mtctx->jobs[wJobID].frameChecksumNeeded) {
      U32 const checksum = (U32)XXH64_digest(&mtctx->serial.xxhState);
      DEBUGLOG(4, "ZSTDMT_flushProduced: writing checksum : %08X \n", checksum);
      MEM_writeLE32((char*)mtctx->jobs[wJobID].dstBuff.start + mtctx->jobs[wJobID].cSize, checksum);
      cSize += 4;
      mtctx->jobs[wJobID].cSize += 4; /* can write this shared value, as worker is no longer active */
      mtctx->jobs[wJobID].frameChecksumNeeded = 0;
    }

    if (cSize > 0) { /* compression is ongoing or completed */
      size_t const toFlush = MIN(cSize - mtctx->jobs[wJobID].dstFlushed, output->size - output->pos);
      DEBUGLOG(5,
          "ZSTDMT_flushProduced: Flushing %u bytes from job %u (completion:%u/%u, generated:%u)",
          (U32)toFlush,
          mtctx->doneJobID,
          (U32)srcConsumed,
          (U32)srcSize,
          (U32)cSize);
      assert(mtctx->doneJobID < mtctx->nextJobID);
      assert(cSize >= mtctx->jobs[wJobID].dstFlushed);
      assert(mtctx->jobs[wJobID].dstBuff.start != NULL);
      memcpy((char*)output->dst + output->pos,
          (const char*)mtctx->jobs[wJobID].dstBuff.start + mtctx->jobs[wJobID].dstFlushed,
          toFlush);
      output->pos += toFlush;
      mtctx->jobs[wJobID].dstFlushed += toFlush; /* can write : this value is only used by mtctx */

      if ((srcConsumed == srcSize)                        /* job is completed */
          && (mtctx->jobs[wJobID].dstFlushed == cSize)) { /* output buffer fully flushed => free this job position */
        DEBUGLOG(5,
            "Job %u completed (%u bytes), moving to next one",
            mtctx->doneJobID,
            (U32)mtctx->jobs[wJobID].dstFlushed);
        ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[wJobID].dstBuff);
        DEBUGLOG(5, "dstBuffer released");
        mtctx->jobs[wJobID].dstBuff = g_nullBuffer;
        mtctx->jobs[wJobID].cSize = 0; /* ensure this job slot is considered "not started" in future check */
        mtctx->consumed += srcSize;
        mtctx->produced += cSize;
        mtctx->doneJobID++;
      }
    }

    /* return value : how many bytes left in buffer ; fake it to 1 when unknown but >0 */
    if (cSize > mtctx->jobs[wJobID].dstFlushed)
      return (cSize - mtctx->jobs[wJobID].dstFlushed);
    if (srcSize > srcConsumed)
      return 1; /* current job not completely compressed */
  }
  if (mtctx->doneJobID < mtctx->nextJobID)
    return 1; /* some more jobs ongoing */
  if (mtctx->jobReady)
    return 1; /* one job is ready to push, just not yet in the list */
  if (mtctx->inBuff.filled > 0)
    return 1; /* input is not empty, and still needs to be converted into a job */
  mtctx->allJobsCompleted =
      mtctx->frameEnded; /* all jobs are entirely flushed => if this one is last one, frame is completed */
  if (end == ZSTD_e_end)
    return !mtctx->frameEnded; /* for ZSTD_e_end, question becomes : is frame completed ? instead of : are internal
                                  buffers fully flushed ? */
  return 0;                    /* internal buffers fully flushed */
}

/**
 * Returns the range of data used by the earliest job that is not yet complete.
 * If the data of the first job is broken up into two segments, we cover both
 * sections.
 */
static range_t ZSTDMT_getInputDataInUse(ZSTDMT_CCtx* mtctx)
{
  unsigned const firstJobID = mtctx->doneJobID;
  unsigned const lastJobID = mtctx->nextJobID;
  unsigned jobID;

  for (jobID = firstJobID; jobID < lastJobID; ++jobID) {
    unsigned const wJobID = jobID & mtctx->jobIDMask;
    size_t consumed;

    ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[wJobID].job_mutex);
    consumed = mtctx->jobs[wJobID].consumed;
    ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);

    if (consumed < mtctx->jobs[wJobID].src.size) {
      range_t range = mtctx->jobs[wJobID].prefix;
      if (range.size == 0) {
        /* Empty prefix */
        range = mtctx->jobs[wJobID].src;
      }
      /* Job source in multiple segments not supported yet */
      assert(range.start <= mtctx->jobs[wJobID].src.start);
      return range;
    }
  }
  return kNullRange;
}

/**
 * Returns non-zero iff buffer and range overlap.
 */
static int ZSTDMT_isOverlapped(buffer_t buffer, range_t range)
{
  BYTE const* const bufferStart = (BYTE const*)buffer.start;
  BYTE const* const bufferEnd = bufferStart + buffer.capacity;
  BYTE const* const rangeStart = (BYTE const*)range.start;
  BYTE const* const rangeEnd = rangeStart + range.size;

  if (rangeStart == NULL || bufferStart == NULL)
    return 0;
  /* Empty ranges cannot overlap */
  if (bufferStart == bufferEnd || rangeStart == rangeEnd)
    return 0;

  return bufferStart < rangeEnd && rangeStart < bufferEnd;
}

static int ZSTDMT_doesOverlapWindow(buffer_t buffer, ZSTD_window_t window)
{
  range_t extDict;
  range_t prefix;

  DEBUGLOG(5, "ZSTDMT_doesOverlapWindow");
  extDict.start = window.dictBase + window.lowLimit;
  extDict.size = window.dictLimit - window.lowLimit;

  prefix.start = window.base + window.dictLimit;
  prefix.size = window.nextSrc - (window.base + window.dictLimit);
  DEBUGLOG(5, "extDict [0x%zx, 0x%zx)", (size_t)extDict.start, (size_t)extDict.start + extDict.size);
  DEBUGLOG(5, "prefix  [0x%zx, 0x%zx)", (size_t)prefix.start, (size_t)prefix.start + prefix.size);

  return ZSTDMT_isOverlapped(buffer, extDict) || ZSTDMT_isOverlapped(buffer, prefix);
}

static void ZSTDMT_waitForLdmComplete(ZSTDMT_CCtx* mtctx, buffer_t buffer)
{
  if (mtctx->params.ldmParams.enableLdm) {
    ZSTD_pthread_mutex_t* mutex = &mtctx->serial.ldmWindowMutex;
    DEBUGLOG(5, "ZSTDMT_waitForLdmComplete");
    DEBUGLOG(5, "source  [0x%zx, 0x%zx)", (size_t)buffer.start, (size_t)buffer.start + buffer.capacity);
    ZSTD_PTHREAD_MUTEX_LOCK(mutex);
    while (ZSTDMT_doesOverlapWindow(buffer, mtctx->serial.ldmWindow)) {
      DEBUGLOG(5, "Waiting for LDM to finish...");
      ZSTD_pthread_cond_wait(&mtctx->serial.ldmWindowCond, mutex);
    }
    DEBUGLOG(6, "Done waiting for LDM to finish");
    ZSTD_pthread_mutex_unlock(mutex);
  }
}

/**
 * Attempts to set the inBuff to the next section to fill.
 * If any part of the new section is still in use we give up.
 * Returns non-zero if the buffer is filled.
 */
static int ZSTDMT_tryGetInputRange(ZSTDMT_CCtx* mtctx)
{
  range_t const inUse = ZSTDMT_getInputDataInUse(mtctx);
  size_t const spaceLeft = mtctx->roundBuff.capacity - mtctx->roundBuff.pos;
  size_t const target = mtctx->targetSectionSize;
  buffer_t buffer;

  DEBUGLOG(5, "ZSTDMT_tryGetInputRange");
  assert(mtctx->inBuff.buffer.start == NULL);
  assert(mtctx->roundBuff.capacity >= target);

  if (spaceLeft < target) {
    /* ZSTD_invalidateRepCodes() doesn't work for extDict variants.
     * Simply copy the prefix to the beginning in that case.
     */
    BYTE* const start = (BYTE*)mtctx->roundBuff.buffer;
    size_t const prefixSize = mtctx->inBuff.prefix.size;

    buffer.start = start;
    buffer.capacity = prefixSize;
    if (ZSTDMT_isOverlapped(buffer, inUse)) {
      DEBUGLOG(5, "Waiting for buffer...");
      return 0;
    }
    ZSTDMT_waitForLdmComplete(mtctx, buffer);
    memmove(start, mtctx->inBuff.prefix.start, prefixSize);
    mtctx->inBuff.prefix.start = start;
    mtctx->roundBuff.pos = prefixSize;
  }
  buffer.start = mtctx->roundBuff.buffer + mtctx->roundBuff.pos;
  buffer.capacity = target;

  if (ZSTDMT_isOverlapped(buffer, inUse)) {
    DEBUGLOG(5, "Waiting for buffer...");
    return 0;
  }
  assert(!ZSTDMT_isOverlapped(buffer, mtctx->inBuff.prefix));

  ZSTDMT_waitForLdmComplete(mtctx, buffer);

  DEBUGLOG(5,
      "Using prefix range [%zx, %zx)",
      (size_t)mtctx->inBuff.prefix.start,
      (size_t)mtctx->inBuff.prefix.start + mtctx->inBuff.prefix.size);
  DEBUGLOG(5, "Using source range [%zx, %zx)", (size_t)buffer.start, (size_t)buffer.start + buffer.capacity);

  mtctx->inBuff.buffer = buffer;
  mtctx->inBuff.filled = 0;
  assert(mtctx->roundBuff.pos + buffer.capacity <= mtctx->roundBuff.capacity);
  return 1;
}

typedef struct {
  size_t toLoad; /* The number of bytes to load from the input. */
  int flush;     /* Boolean declaring if we must flush because we found a synchronization point. */
} syncPoint_t;

/**
 * Searches through the input for a synchronization point. If one is found, we
 * will instruct the caller to flush, and return the number of bytes to load.
 * Otherwise, we will load as many bytes as possible and instruct the caller
 * to continue as normal.
 */
static syncPoint_t findSynchronizationPoint(ZSTDMT_CCtx const* mtctx, ZSTD_inBuffer const input)
{
  BYTE const* const istart = (BYTE const*)input.src + input.pos;
  U64 const primePower = mtctx->rsync.primePower;
  U64 const hitMask = mtctx->rsync.hitMask;

  syncPoint_t syncPoint;
  U64 hash;
  BYTE const* prev;
  size_t pos;

  syncPoint.toLoad = MIN(input.size - input.pos, mtctx->targetSectionSize - mtctx->inBuff.filled);
  syncPoint.flush = 0;
  if (!mtctx->params.rsyncable)
    /* Rsync is disabled. */
    return syncPoint;
  if (mtctx->inBuff.filled + syncPoint.toLoad < RSYNC_LENGTH)
    /* Not enough to compute the hash.
     * We will miss any synchronization points in this RSYNC_LENGTH byte
     * window. However, since it depends only in the internal buffers, if the
     * state is already synchronized, we will remain synchronized.
     * Additionally, the probability that we miss a synchronization point is
     * low: RSYNC_LENGTH / targetSectionSize.
     */
    return syncPoint;
  /* Initialize the loop variables. */
  if (mtctx->inBuff.filled >= RSYNC_LENGTH) {
    /* We have enough bytes buffered to initialize the hash.
     * Start scanning at the beginning of the input.
     */
    pos = 0;
    prev = (BYTE const*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled - RSYNC_LENGTH;
    hash = ZSTD_rollingHash_compute(prev, RSYNC_LENGTH);
  } else {
    /* We don't have enough bytes buffered to initialize the hash, but
     * we know we have at least RSYNC_LENGTH bytes total.
     * Start scanning after the first RSYNC_LENGTH bytes less the bytes
     * already buffered.
     */
    pos = RSYNC_LENGTH - mtctx->inBuff.filled;
    prev = (BYTE const*)mtctx->inBuff.buffer.start - pos;
    hash = ZSTD_rollingHash_compute(mtctx->inBuff.buffer.start, mtctx->inBuff.filled);
    hash = ZSTD_rollingHash_append(hash, istart, pos);
  }
  /* Starting with the hash of the previous RSYNC_LENGTH bytes, roll
   * through the input. If we hit a synchronization point, then cut the
   * job off, and tell the compressor to flush the job. Otherwise, load
   * all the bytes and continue as normal.
   * If we go too long without a synchronization point (targetSectionSize)
   * then a block will be emitted anyways, but this is okay, since if we
   * are already synchronized we will remain synchronized.
   */
  for (; pos < syncPoint.toLoad; ++pos) {
    BYTE const toRemove = pos < RSYNC_LENGTH ? prev[pos] : istart[pos - RSYNC_LENGTH];
    /* if (pos >= RSYNC_LENGTH) assert(ZSTD_rollingHash_compute(istart + pos - RSYNC_LENGTH, RSYNC_LENGTH) == hash); */
    hash = ZSTD_rollingHash_rotate(hash, toRemove, istart[pos], primePower);
    if ((hash & hitMask) == hitMask) {
      syncPoint.toLoad = pos + 1;
      syncPoint.flush = 1;
      break;
    }
  }
  return syncPoint;
}

size_t ZSTDMT_nextInputSizeHint(const ZSTDMT_CCtx* mtctx)
{
  size_t hintInSize = mtctx->targetSectionSize - mtctx->inBuff.filled;
  if (hintInSize == 0)
    hintInSize = mtctx->targetSectionSize;
  return hintInSize;
}

/** ZSTDMT_compressStream_generic() :
 *  internal use only - exposed to be invoked from zstd_compress.c
 *  assumption : output and input are valid (pos <= size)
 * @return : minimum amount of data remaining to flush, 0 if none */
size_t ZSTDMT_compressStream_generic(
    ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_inBuffer* input, ZSTD_EndDirective endOp)
{
  unsigned forwardInputProgress = 0;
  DEBUGLOG(5, "ZSTDMT_compressStream_generic (endOp=%u, srcSize=%u)", (U32)endOp, (U32)(input->size - input->pos));
  assert(output->pos <= output->size);
  assert(input->pos <= input->size);

  if (mtctx->singleBlockingThread) { /* delegate to single-thread (synchronous) */
    return ZSTD_compressStream_generic(mtctx->cctxPool->cctx[0], output, input, endOp);
  }

  if ((mtctx->frameEnded) && (endOp == ZSTD_e_continue)) {
    /* current frame being ended. Only flush/end are allowed */
    return ERROR(stage_wrong);
  }

  /* single-pass shortcut (note : synchronous-mode) */
  if ((!mtctx->params.rsyncable)     /* rsyncable mode is disabled */
      && (mtctx->nextJobID == 0)     /* just started */
      && (mtctx->inBuff.filled == 0) /* nothing buffered */
      && (!mtctx->jobReady)          /* no job already created */
      && (endOp == ZSTD_e_end)       /* end order */
      && (output->size - output->pos >= ZSTD_compressBound(input->size - input->pos))) { /* enough space in dst */
    size_t const cSize = ZSTDMT_compress_advanced_internal(mtctx,
        (char*)output->dst + output->pos,
        output->size - output->pos,
        (const char*)input->src + input->pos,
        input->size - input->pos,
        mtctx->cdict,
        mtctx->params);
    if (ZSTD_isError(cSize))
      return cSize;
    input->pos = input->size;
    output->pos += cSize;
    mtctx->allJobsCompleted = 1;
    mtctx->frameEnded = 1;
    return 0;
  }

  /* fill input buffer */
  if ((!mtctx->jobReady) && (input->size > input->pos)) { /* support NULL input */
    if (mtctx->inBuff.buffer.start == NULL) {
      assert(mtctx->inBuff.filled == 0); /* Can't fill an empty buffer */
      if (!ZSTDMT_tryGetInputRange(mtctx)) {
        /* It is only possible for this operation to fail if there are
         * still compression jobs ongoing.
         */
        DEBUGLOG(5, "ZSTDMT_tryGetInputRange failed");
        assert(mtctx->doneJobID != mtctx->nextJobID);
      } else
        DEBUGLOG(5,
            "ZSTDMT_tryGetInputRange completed successfully : mtctx->inBuff.buffer.start = %p",
            mtctx->inBuff.buffer.start);
    }
    if (mtctx->inBuff.buffer.start != NULL) {
      syncPoint_t const syncPoint = findSynchronizationPoint(mtctx, *input);
      if (syncPoint.flush && endOp == ZSTD_e_continue) {
        endOp = ZSTD_e_flush;
      }
      assert(mtctx->inBuff.buffer.capacity >= mtctx->targetSectionSize);
      DEBUGLOG(5,
          "ZSTDMT_compressStream_generic: adding %u bytes on top of %u to buffer of size %u",
          (U32)syncPoint.toLoad,
          (U32)mtctx->inBuff.filled,
          (U32)mtctx->targetSectionSize);
      memcpy((char*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled,
          (const char*)input->src + input->pos,
          syncPoint.toLoad);
      input->pos += syncPoint.toLoad;
      mtctx->inBuff.filled += syncPoint.toLoad;
      forwardInputProgress = syncPoint.toLoad > 0;
    }
    if ((input->pos < input->size) && (endOp == ZSTD_e_end))
      endOp = ZSTD_e_flush; /* can't end now : not all input consumed */
  }

  if ((mtctx->jobReady) || (mtctx->inBuff.filled >= mtctx->targetSectionSize) /* filled enough : let's compress */
      || ((endOp != ZSTD_e_continue) && (mtctx->inBuff.filled > 0))           /* something to flush : let's go */
      || ((endOp == ZSTD_e_end) && (!mtctx->frameEnded))) { /* must finish the frame with a zero-size block */
    size_t const jobSize = mtctx->inBuff.filled;
    assert(mtctx->inBuff.filled <= mtctx->targetSectionSize);
    CHECK_F(ZSTDMT_createCompressionJob(mtctx, jobSize, endOp));
  }

  /* check for potential compressed data ready to be flushed */
  {
    size_t const remainingToFlush = ZSTDMT_flushProduced(
        mtctx, output, !forwardInputProgress, endOp); /* block if there was no forward input progress */
    if (input->pos < input->size)
      return MAX(remainingToFlush, 1); /* input not consumed : do not end flush yet */
    DEBUGLOG(5, "end of ZSTDMT_compressStream_generic: remainingToFlush = %u", (U32)remainingToFlush);
    return remainingToFlush;
  }
}

size_t ZSTDMT_compressStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
{
  CHECK_F(ZSTDMT_compressStream_generic(mtctx, output, input, ZSTD_e_continue));

  /* recommended next input size : fill current input buffer */
  return mtctx->targetSectionSize - mtctx->inBuff.filled; /* note : could be zero when input buffer is fully filled and
                                                             no more availability to create new job */
}

static size_t ZSTDMT_flushStream_internal(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_EndDirective endFrame)
{
  size_t const srcSize = mtctx->inBuff.filled;
  DEBUGLOG(5, "ZSTDMT_flushStream_internal");

  if (mtctx->jobReady                                        /* one job ready for a worker to pick up */
      || (srcSize > 0)                                       /* still some data within input buffer */
      || ((endFrame == ZSTD_e_end) && !mtctx->frameEnded)) { /* need a last 0-size block to end frame */
    DEBUGLOG(5, "ZSTDMT_flushStream_internal : create a new job (%u bytes, end:%u)", (U32)srcSize, (U32)endFrame);
    CHECK_F(ZSTDMT_createCompressionJob(mtctx, srcSize, endFrame));
  }

  /* check if there is any data available to flush */
  return ZSTDMT_flushProduced(mtctx, output, 1 /* blockToFlush */, endFrame);
}

size_t ZSTDMT_flushStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output)
{
  DEBUGLOG(5, "ZSTDMT_flushStream");
  if (mtctx->singleBlockingThread)
    return ZSTD_flushStream(mtctx->cctxPool->cctx[0], output);
  return ZSTDMT_flushStream_internal(mtctx, output, ZSTD_e_flush);
}

size_t ZSTDMT_endStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output)
{
  DEBUGLOG(4, "ZSTDMT_endStream");
  if (mtctx->singleBlockingThread)
    return ZSTD_endStream(mtctx->cctxPool->cctx[0], output);
  return ZSTDMT_flushStream_internal(mtctx, output, ZSTD_e_end);
}
